Codeigniter and PHP Interview questions

Top 200 PHP interview questions and answers are below

Questions : 1	Who is the father of PHP ?
Answers : 1	Rasmus Lerdorf is known as the father of PHP.
Questions : 2	What is the difference between $name and $$name?
Answers : 2	$name is variable where as $$name is reference variable like $name=sonia and $$name=singh so $sonia value is singh.
Questions : 3	How can we submit a form without a submit button?
Answer : 3	Java script submit() function is used for submit form without submit button on click call document.formname.submit()
Questions : 4	In how many ways we can retrieve the data in the result set of MySQL using PHP?
Answer : 4	We can do it by 4 Ways 1. mysql_fetch_row. , 2. mysql_fetch_array , 3. mysql_fetch_object 4. mysql_fetch_assoc
Questions : 5	What is the difference between mysql_fetch_object and mysql_fetch_array?
Answers : 5	mysql_fetch_object() is similar tomysql_fetch_array(), with one difference - an object is returned, instead of an array. Indirectly, that means that you can only access the data by the field names, and not by their offsets (numbers are illegal property names).
Questions : 6	What are the differences between Get and post methods.
Answers : 6	There are some defference between GET and POST method 1. GET Method have some limit like only 2Kb data able to send for request But in POST method unlimited data can we send 2. when we use GET method requested data show in url but Not in POST method so POST method is good for send sensetive request
Questions : 7	How can we extract string "pcds.co.in " from a string "http://info@pcds.co.in using regular expression of PHP?
Answers : 7	preg_match("/^http:\/\/.+@(.+)$/","http://info@pcds.co.in",$matches); echo $matches[1];
Questions : 8	How can we create a database using PHP and MySQL?
Answers : 8	We can create MySQL database with the use of mysql_create_db("Database Name")
Questions : 9	What are the differences between require and include?
Answers : 9	Both include and require used to include a file but when included file not found Include send Warning where as Require send Fatal Error .
Questions : 10	Can we use include ("xyz.PHP") two times in a PHP page "index.PHP"?
Answers : 10	Yes we can use include("xyz.php") more than one time in any page. but it create a prob when xyz.php file contain some funtions declaration then error will come for already declared function in this file else not a prob like if you want to show same content two time in page then must incude it two time not a prob
Questions : 11	What are the different tables(Engine) present in MySQL, which one is default?
Answers : 11	Following tables (Storage Engine) we can create 1. MyISAM(The default storage engine IN MYSQL Each MyISAM table is stored on disk in three files. The files have names that begin with the table name and have an extension to indicate the file type. An .frm file stores the table format. The data file has an .MYD (MYData) extension. The index file has an .MYI (MYIndex) extension. ) 2. InnoDB(InnoDB is a transaction-safe (ACID compliant) storage engine for MySQL that has commit, rollback, and crash-recovery capabilities to protect user data.) 3. Merge 4. Heap (MEMORY)(The MEMORY storage engine creates tables with contents that are stored in memory. Formerly, these were known as HEAP tables. MEMORY is the preferred term, although HEAP remains supported for backward compatibility. ) 5. BDB (BerkeleyDB)(Sleepycat Software has provided MySQL with the Berkeley DB transactional storage engine. This storage engine typically is called BDB for short. BDB tables may have a greater chance of surviving crashes and are also capable of COMMIT and ROLLBACK operations on transactions) 6. EXAMPLE  7. FEDERATED (It is a storage engine that accesses data in tables of remote databases rather than in local tables. ) 8. ARCHIVE (The ARCHIVE storage engine is used for storing large amounts of data without indexes in a very small footprint. ) 9. CSV (The CSV storage engine stores data in text files using comma-separated values format.) 10. BLACKHOLE (The BLACKHOLE storage engine acts as a "black hole" that accepts data but throws it away and does not store it. Retrievals always return an empty result)
Questions : 12	What is use of header() function in php ?
Answers : 12	The header() function sends a raw HTTP header to a client.We can use herder() function for redirection of pages. It is important to notice that header() must be called before any actual output is seen..
Questions : 13	How can I execute a PHP script using command line?
Answers : 13	Just run the PHP CLI (Command Line Interface) program and provide the PHP script file name as the command line argument.
Questions : 14	Suppose your Zend engine supports the mode <? ?> Then how can u configure your PHP Zend engine to support <?PHP ?> mode ?
Answers : 14	In php.ini file: set short_open_tag=on to make PHP support
Questions : 15	Shopping cart online validation i.e. how can we configure Paypal, etc.?
Answers : 15	Nothing more we have to do only redirect to the payPal url after submit all information needed by paypal like amount,adresss etc.
Questions : 16	What is meant by nl2br()?
Answers : 16	Inserts HTML line breaks (<BR />) before all newlines in a string.
Questions : 17	What is htaccess? Why do we use this and Where?
Answers : 17	.htaccess files are configuration files of Apache Server which provide a way to make configuration changes on a per-directory basis. A file, containing one or more configuration directives, is placed in a particular document directory, and the directives apply to that directory, and all subdirectories thereof.
Questions : 18	How we get IP address of client, previous reference page etc ?
Answers : 18	By using $_SERVER['REMOTE_ADDR'],$_SERVER['HTTP_REFERER'] etc.
Questions : 19	What are the reasons for selecting lamp (Linux, apache, MySQL, PHP) instead of combination of other software programs, servers and operating systems?
Answers : 19	All of those are open source resource. Security of Linux is very very more than windows. Apache is a better server that IIS both in functionality and security. MySQL is world most popular open source database. PHP is more faster that asp or any other scripting language.
Questions : 20	How can we encrypt and decrypt a data present in a MySQL table using MySQL?
Answers : 20	AES_ENCRYPT () and AES_DECRYPT ()
Questions : 21	How can we encrypt the username and password using PHP?
Answers : 21	The functions in this section perform encryption and decryption, and compression and uncompression: encryption decryption AES_ENCRYT() AES_DECRYPT() ENCODE() DECODE() DES_ENCRYPT() DES_DECRYPT() ENCRYPT() Not available MD5() Not available OLD_PASSWORD() Not available PASSWORD() Not available SHA() or SHA1() Not available Not available UNCOMPRESSED_LENGTH()
Questions : 22	What are the features and advantages of object-oriented programming?
Answers : 22	One of the main advantages of OO programming is its ease of modification; objects can easily be modified and added to a system there by reducing maintenance costs. OO programming is also considered to be better at modeling the real world than is procedural programming. It allows for more complicated and flexible interactions. OO systems are also easier for non-technical personnel to understand and easier for them to participate in the maintenance and enhancement of a system because it appeals to natural human cognition patterns. For some systems, an OO approach can speed development time since many objects are standard across systems and can be reused. Components that manage dates, shipping, shopping carts, etc. can be purchased and easily modified for a specific system
Questions : 23	What are the differences between procedure-oriented languages and object-oriented languages?
Answers : 23	There are lot of difference between procedure language and object oriented like below 1>Procedure language easy for new developer but complex to understand whole software as compare to object oriented model 2>In Procedure language it is difficult to use design pattern mvc , Singleton pattern etc but in OOP you we able to develop design pattern 3>IN OOP language we able to ree use code like Inheritance ,polymorphism etc but this type of thing not available in procedure language on that our Fonda use COPY and PASTE .
Questions : 24	What is the use of friend function?
Answers : 24	Sometimes a function is best shared among a number of different classes. Such functions can be declared either as member functions of one class or as global functions. In either case they can be set to be friends of other classes, by using a friend specifier in the class that is admitting them. Such functions can use all attributes of the class which names them as a friend, as if they were themselves members of that class. A friend declaration is essentially a prototype for a member function, but instead of requiring an implementation with the name of that class attached by the double colon syntax, a global function or member function of another class provides the match.
Questions : 25	What are the differences between public, private, protected, static, transient, final and volatile?
Answer : 25	Public: Public declared items can be accessed everywhere. Protected: Protected limits access to inherited and parent classes (and to the class that defines the item). Private: Private limits visibility only to the class that defines the item. Static: A static variable exists only in a local function scope, but it does not lose its value when program execution leaves this scope. Final: Final keyword prevents child classes from overriding a method by prefixing the definition with final. If the class itself is being defined final then it cannot be extended. transient: A transient variable is a variable that may not be serialized.  volatile: a variable that might be concurrently modified by multiple threads should be declared volatile. Variables declared to be volatile will not be optimized by the compiler because their value can change at any time.
Questions : 26	What are the different types of errors in PHP?
Answer : 26	Three are three types of errors:1. Notices: These are trivial, non-critical errors that PHP encounters while executing a script – for example, accessing a variable that has not yet been defined. By default, such errors are not displayed to the user at all – although, as you will see, you can change this default behavior.2. Warnings: These are more serious errors – for example, attempting to include() a file which does not exist. By default, these errors are displayed to the user, but they do not result in script termination.3. Fatal errors: These are critical errors – for example, instantiating an object of a non-existent class, or calling a non-existent function. These errors cause the immediate termination of the script, and PHP's default behavior is to display them to the user when they take place.
Questions : 27	What is the functionality of the function strstr and stristr?
Answers : 27	strstr Returns part of string from the first occurrence of needle(sub string that we finding out ) to the end of string. $email= 'sonialouder@gmail.com'; $domain = strstr($email, '@'); echo $domain; // prints @gmail.com here @ is the needle stristr is case-insensitive means able not able to diffrenciate between a and A
Questions : 28	What are the differences between PHP 3 and PHP 4 and PHP 5?
Answer : 28	There are lot of difference among these three version of php 1>Php3 is oldest version after that php4 came and current version is php5 (php5.3) where php6 have to come 2>Difference mean oldest version have less functionality as compare to new one like php5 have all OOPs concept now where as php3 was pure procedural language constructive like C In PHP5 1. Implementation of exceptions and exception handling 2. Type hinting which allows you to force the type of a specific argument 3. Overloading of methods through the __call function 4. Full constructors and destructors etc through a __constuctor and __destructor function 5. __autoload function for dynamically including certain include files depending on the class you are trying to create. 6 Finality : can now use the final keyword to indicate that a method cannot be overridden by a child. You can also declare an entire class as final which prevents it from having any children at all. 7 Interfaces & Abstract Classes 8 Passed by Reference : 9 An __clone method if you really want to duplicate an object 10 Numbers of Functions Deprecated in php 5.x like ereg,ereg_replace,magic_quotes_runtime, session_register,register_globals, split(), call_user_method() etc
Questions : 29	How can we convert asp pages to PHP pages?
Answer : 29	there are lots of tools available for asp to PHP conversion. you can search Google for that. the best one is available athttp://asp2php.naken.cc./
Questions : 30	What is the functionality of the function htmlentities?
Answer : 30	Convert all applicable characters to HTML entities This function is identical to htmlspecialchars() in all ways, except with htmlentities(), all characters which have HTML character entity equivalents are translated into these entities.
Questions : 31	How can we get second of the current time using date function?
Answer : 31	$second = date("s");
Questions : 32	How can we convert the time zones using PHP?
Answer : 32	By using date_default_timezone_get and  date_default_timezone_set function on PHP 5.1.0 <?php // Discover what 8am in Tokyo relates to on the East Coast of the US // Set the default timezone to Tokyo time: date_default_timezone_set('Asia/Tokyo'); // Now generate the timestamp for that particular timezone, on Jan 1st, 2000 $stamp = mktime(8, 0, 0, 1, 1, 2000); // Now set the timezone back to US/Eastern date_default_timezone_set('US/Eastern'); // Output the date in a standard format (RFC1123), this will print: // Fri, 31 Dec 1999 18:00:00 EST echo '<p>', date(DATE_RFC1123, $stamp) ,'</p>';?>
Questions : 33	What is meant by urlencode and urldocode?
Answer : 33	URLencode returns a string in which all non-alphanumeric characters except -_. have been replaced with a percent (%) sign followed by two hex digits and spaces encoded as plus (+) signs. It is encoded the same way that the posted data from a WWW form is encoded, that is the same way as in  application/x-www-form-urlencoded media type. urldecode decodes any %## encoding in the given string.
Questions : 34	What is the difference between the functions unlink and unset?
Answer : 34	unlink() deletes the given file from the file system. unset() makes a variable undefined.
Questions : 35	How can we register the variables into a session?
Answer : 35	$_SESSION['name'] = "sonia";
Questions : 36	How can we get the properties (size, type, width, height) of an image using PHP image functions?
Answer : 36	To know the Image type use exif_imagetype () function To know the Image size use getimagesize () function To know the image width use imagesx () function To know the image height use imagesy() function t
Questions : 37	How can we get the browser properties using PHP?
Answer : 37	By using  $_SERVER['HTTP_USER_AGENT'] variable.
Questions : 38	What is the maximum size of a file that can be uploaded using PHP and how can we change this?
Answer : 38	By default the maximum size is 2MB. and we can change the following setup at php.iniupload_max_filesize = 2M
Questions : 39	How can we increase the execution time of a PHP script?
Answer : 39	by changing the following setup at php.inimax_execution_time = 30 ; Maximum execution time of each script, in seconds
Questions : 40	How can we take a backup of a MySQL table and how can we restore it. ?
Answer : 40	To backup: BACKUP TABLE tbl_name[,tbl_name…] TO '/path/to/backup/directory' RESTORE TABLE tbl_name[,tbl_name…] FROM '/path/to/backup/directory'mysqldump: Dumping Table Structure and DataUtility to dump a database or a collection of database for backup or for transferring the data to another SQL server (not necessarily a MySQL server). The dump will contain SQL statements to create the table and/or populate the table. -t, –no-create-info Don't write table creation information (the CREATE TABLE statement). -d, –no-data Don't write any row information for the table. This is very useful if you just want to get a dump of the structure for a table!
Questions : 41	How can we optimize or increase the speed of a MySQL select query?
Answer : 41	first of all instead of using select * from table1, use select column1, column2, column3.. from table1 Look for the opportunity to introduce index in the table you are querying. use limit keyword if you are looking for any specific number of rows from the result set.
Questions : 42	How many ways can we get the value of current session id?
Answer : 42	session_id() returns the session id for the current session.
Questions : 43	How can we destroy the session, how can we unset the variable of a session?
Answer : 43	session_unregister — Unregister a global variable from the current session session_unset — Free all session variables
Questions : 44	How can we set and destroy the cookie n php?
Answer : 44	By using setcookie(name, value, expire, path, domain); function we can set the cookie in php ; Set the cookies in past for destroy. like setcookie("user", "sonia", time()+3600); for set the cookie setcookie("user", "", time()-3600); for destroy or delete the cookies;
Questions : 45	How many ways we can pass the variable through the navigation between the pages?
Answer : 45	GET/QueryString POST
Questions : 46	What is the difference between ereg_replace() and eregi_replace()?
Answer : 46	eregi_replace() function is identical to ereg_replace() except that this ignores case distinction when matching alphabetic characters.eregi_replace() function is identical to ereg_replace() except that this ignores case distinction when matching alphabetic characters.
Questions : 47	What are the different functions in sorting an array?
Answer : 47	Sort(), arsort(), asort(), ksort(), natsort(), natcasesort(), rsort(), usort(), array_multisort(), and uksort().
Questions : 48	How can we know the count/number of elements of an array?
Answer : 48	2 ways a) sizeof($urarray) This function is an alias of count() b) count($urarray)
Questions : 49	what is session_set_save_handler in PHP?
Answer : 49	session_set_save_handler() sets the user-level session storage functions which are used for storing and retrieving data associated with a session. This is most useful when a storage method other than those supplied by PHP sessions is preferred. i.e. Storing the session data in a local database.
Questions : 50	How can I know that a variable is a number or not using a JavaScript?
Answer : 50	bool is_numeric ( mixed var) Returns TRUE if var is a number or a numeric string, FALSE otherwise.or use isNaN(mixed var)The isNaN() function is used to check if a value is not a number.
Questions : 51	List out some tools through which we can draw E-R diagrams for mysql.
Answer : 51	Case Studio Smart Draw
Questions : 52	How can I retrieve values from one database server and store them in other database server using PHP?
Answer : 52	we can always fetch from one database and rewrite to another. here is a nice solution of it.$db1 = mysql_connect("host","user","pwd") mysql_select_db("db1", $db1); $res1 = mysql_query("query",$db1);$db2 = mysql_connect("host","user","pwd") mysql_select_db("db2", $db2); $res2 = mysql_query("query",$db2);At this point you can only fetch records from you previous ResultSet, i.e $res1 – But you cannot execute new query in $db1, even if you supply the link as because the link was overwritten by the new db.so at this point the following script will fail $res3 = mysql_query("query",$db1); //this will failSo how to solve that? take a look below. $db1 = mysql_connect("host","user","pwd") mysql_select_db("db1", $db1); $res1 = mysql_query("query",$db1); $db2 = mysql_connect("host","user","pwd", true) mysql_select_db("db2", $db2); $res2 = mysql_query("query",$db2); So mysql_connect has another optional boolean parameter which indicates whether a link will be created or not. as we connect to the $db2 with this optional parameter set to 'true', so both link will remain live. now the following query will execute successfully. $res3 = mysql_query("query",$db1);
Questions : 53	List out the predefined classes in PHP?
Answer : 53	Directory stdClass __PHP_Incomplete_Class exception php_user_filter
Questions : 54	How can I make a script that can be bi-language (supports English, German)?
Answer : 54	You can maintain two separate language file for each of the language. all the labels are putted in both language files as variables and assign those variables in the PHP source. on runtime choose the required language option.
Questions : 55	What are the difference between abstract class and interface?
Answer : 55	Abstract class: abstract classes are the class where one or more methods are abstract but not necessarily all method has to be abstract. Abstract methods are the methods, which are declare in its class but not define. The definition of those methods must be in its extending class.Interface: Interfaces are one type of class where all the methods are abstract. That means all the methods only declared but not defined. All the methods must be define by its implemented class.
Questions : 56	How can we send mail using JavaScript?
Answer : 56	JavaScript does not have any networking capabilities as it is designed to work on client site. As a result we can not send mails using JavaScript. But we can call the client side mail protocol mailto via JavaScript to prompt for an email to send. this requires the client to approve it.
Questions : 57	How can we repair a MySQL table?
Answer : 57	The syntex for repairing a MySQL table is REPAIR TABLENAME, [TABLENAME, ], [Quick],[Extended] This command will repair the table specified if the quick is given the MySQL will do a repair of only the index tree if the extended is given it will create index row by row
Questions : 58	What are the advantages of stored procedures, triggers, indexes?
Answer : 58	A stored procedure is a set of SQL commands that can be compiled and stored in the server. Once this has been done, clients don't need to keep re-issuing the entire query but can refer to the stored procedure. This provides better overall performance because the query has to be parsed only once, and less information needs to be sent between the server and the client. You can also raise the conceptual level by having libraries of functions in the server. However, stored procedures of course do increase the load on the database server system, as more of the work is done on the server side and less on the client (application) side.Triggers will also be implemented. A trigger is effectively a type of stored procedure, one that is invoked when a particular event occurs. For example, you can install a stored procedure that is triggered each time a record is deleted from a transaction table and that stored procedure automatically deletes the corresponding customer from a customer table when all his transactions are deleted.Indexes are used to find rows with specific column values quickly. Without an index, MySQL must begin with the first row and then read through the entire table to find the relevant rows. The larger the table, the more this costs. If the table has an index for the columns in question, MySQL can quickly determine the position to seek to in the middle of the data file without having to look at all the data. If a table has 1,000 rows, this is at least 100 times faster than reading sequentially. If you need to access most of the rows, it is faster to read sequentially, because this minimizes disk seeks.
Questions : 59	What is the maximum length of a table name, database name, and fieldname in MySQL?
Answer : 59	The following table describes the maximum length for each type of identifier. Identifier Maximum Length (bytes) Database 64 Table 64 Column 64 Index 64 Alias 255 There are some restrictions on the characters that may appear in identifiers:
Questions : 60	How many values can the SET function of MySQL take?
Answer : 60	MySQL set can take zero or more values but at the maximum it can take 64 values
Questions : 61	What are the other commands to know the structure of table using MySQL commands except explain command?
Answer : 61	describe Table-Name;
Questions : 62	How many tables will create when we create table, what are they?
Answer : 62	The '.frm' file stores the table definition. The data file has a '.MYD' (MYData) extension. The index file has a '.MYI' (MYIndex) extension,
Questions : 63	What is the purpose of the following files having extensions 1) .frm 2) .myd 3) .myi? What do these files contain?
Answer : 63	In MySql, the default table type is MyISAM. Each MyISAM table is stored on disk in three files. The files have names that begin with the table name and have an extension to indicate the file type. The '.frm' file stores the table definition. The data file has a '.MYD' (MYData) extension. The index file has a '.MYI' (MYIndex) extension,
Questions : 64	What is maximum size of a database in MySQL?
Answer : 64	If the operating system or filesystem places a limit on the number of files in a directory, MySQL is bound by that constraint.The efficiency of the operating system in handling large numbers of files in a directory can place a practical limit on the number of tables in a database. If the time required to open a file in the directory increases significantly as the number of files increases, database performance can be adversely affected. The amount of available disk space limits the number of tables. MySQL 3.22 had a 4GB (4 gigabyte) limit on table size. With the MyISAM storage engine in MySQL 3.23, the maximum table size was increased to 65536 terabytes (2567 – 1 bytes). With this larger allowed table size, the maximum effective table size for MySQL databases is usually determined by operating system constraints on file sizes, not by MySQL internal limits.The InnoDB storage engine maintains InnoDB tables within a tablespace that can be created from several files. This allows a table to exceed the maximum individual file size. The tablespace can include raw disk partitions, which allows extremely large tables. The maximum tablespace size is 64TB. The following table lists some examples of operating system file-size limits. This is only a rough guide and is not intended to be definitive. For the most up-to-date information, be sure to check the documentation specific to your operating system. Operating System File-size LimitLinux 2.2-Intel 32-bit 2GB (LFS: 4GB) Linux 2.4+ (using ext3 filesystem) 4TB Solaris 9/10 16TB NetWare w/NSS filesystem 8TB Win32 w/ FAT/FAT32 2GB/4GB Win32 w/ NTFS 2TB (possibly larger) MacOS X w/ HFS+ 2TB
Questions : 65	Give the syntax of Grant and Revoke commands?
Answer : 65	The generic syntax for grant is as following > GRANT [rights] on [database/s] TO [username@hostname] IDENTIFIED BY [password] now rights can be a) All privileges b) combination of create, drop, select, insert, update and delete etc.We can grant rights on all databse by using *.* or some specific database by database.* or a specific table by database.table_name username@hotsname can be either username@localhost, username@hostname and username@% where hostname is any valid hostname and % represents any name, the *.* any condition password is simply the password of userThe generic syntax for revoke is as following > REVOKE [rights] on [database/s] FROM [username@hostname] now rights can be as explained above a) All privileges b) combination of create, drop, select, insert, update and delete etc. username@hotsname can be either username@localhost, username@hostname and username@% where hostname is any valid hostname and % represents any name, the *.* any condition
Questions : 66	Explain Normalization concept?
Answer : 66	The normalization process involves getting our data to conform to three progressive normal forms, and a higher level of normalization cannot be achieved until the previous levels have been achieved (there are actually five normal forms, but the last two are mainly academic and will not be discussed).First Normal FormThe First Normal Form (or 1NF) involves removal of redundant data from horizontal rows. We want to ensure that there is no duplication of data in a given row, and that every column stores the least amount of information possible (making the field atomic).Second Normal FormWhere the First Normal Form deals with redundancy of data across a horizontal row, Second Normal Form (or 2NF) deals with redundancy of data in vertical columns. As stated earlier, the normal forms are progressive, so to achieve Second Normal Form, your tables must already be in First Normal Form.Third Normal Form I have a confession to make; I do not often use Third Normal Form. In Third Normal Form we are looking for data in our tables that is not fully dependant on the primary key, but dependant on another value in the table
Questions : 67	How can we find the number of rows in a table using MySQL?
Answer : 67	Use this for mysql >SELECT COUNT(*) FROM table_name;
Questions : 68	How can we find the number of rows in a result set using PHP?
Answer : 68	$result = mysql_query($sql, $db_link); $num_rows = mysql_num_rows($result); echo "$num_rows rows found";
Questions : 69	How many ways we can we find the current date using MySQL?
Answer : 69	SELECT CURDATE(); CURRENT_DATE() = CURDATE() for time use SELECT CURTIME(); CURRENT_TIME() = CURTIME()
Questions : 70	What are the advantages and disadvantages of Cascading Style Sheets?
Answer : 70	External Style SheetsAdvantagesCan control styles for multiple documents at once. Classes can be created for use on multiple HTML element types in many documents. Selector and grouping methods can be used to apply styles under complex contextsDisadvantagesAn extra download is required to import style information for each document The rendering of the document may be delayed until the external style sheet is loaded Becomes slightly unwieldy for small quantities of style definitionsEmbedded Style Sheets Advantages Classes can be created for use on multiple tag types in the document. Selector and grouping methods can be used to apply styles under complex contexts. No additional downloads necessary to receive style information Disadvantages This method can not control styles for multiple documents at once Inline Styles Advantages Useful for small quantities of style definitions. Can override other style specification methods at the local level so only exceptions need to be listed in conjunction with other style methods Disadvantages Does not distance style information from content (a main goal of SGML/HTML). Can not control styles for multiple documents at once. Author can not create or control classes of elements to control multiple element types within the document. Selector grouping methods can not be used to create complex element addressing scenarios
Questions : 71	What type of inheritance that PHP supports?
Answer : 71	In PHP an extended class is always dependent on a single base class, that is, multiple inheritance is not supported. Classes are extended using the keyword 'extends'.
Questions : 72	What is the difference between Primary Key and Unique key?
Answer : 72	Primary Key: A column in a table whose values uniquely identify the rows in the table. A primary key value cannot be NULL. Unique Key: Unique Keys are used to uniquely identify each row in the table. There can be one and only one row for each unique key value. So NULL can be a unique key.There can be only one primary key for a table but there can be more than one unique for a table.
Question : 73	what is garbage collection? default time ? refresh time?
Answer : 73	Garbage Collection is an automated part of PHP , If the Garbage Collection process runs, it then analyzes any files in the /tmp for any session files that have not been accessed in a certain amount of time and physically deletes them. Garbage Collection process only runs in the default session save directory, which is /tmp. If you opt to save your sessions in a different directory, the Garbage Collection process will ignore it. the Garbage Collection process does not differentiate between which sessions belong to whom when run. This is especially important note on shared web servers. If the process is run, it deletes ALL files that have not been accessed in the directory. There are 3 PHP.ini variables, which deal with the garbage collector: PHP ini value name default session.gc_maxlifetime 1440 seconds or 24 minutes session.gc_probability 1 session.gc_divisor 100
Questions : 74	What are the advantages/disadvantages of MySQL and PHP?
Answer : 74	Both of them are open source software (so free of cost), support cross platform. php is faster then ASP and JSP.
Questions : 75	What is the difference between GROUP BY and ORDER BY in Sql?
Answer : 75	ORDER BY [col1],[col2],…,[coln]; Tels DBMS according to what columns it should sort the result. If two rows will hawe the same value in col1 it will try to sort them according to col2 and so on.GROUP BY [col1],[col2],…,[coln]; Tels DBMS to group results with same value of column col1. You can use COUNT(col1), SUM(col1), AVG(col1) with it, if you want to count all items in group, sum all values or view average
Questions : 76	What is the difference between char and varchar data types?
Answer : 76	Set char to occupy n bytes and it will take n bytes even if u r storing a value of n-m bytes Set varchar to occupy n bytes and it will take only the required space and will not use the n bytes eg. name char(15) will waste 10 bytes if we store 'romharshan', if each char takes a byte eg. name varchar(15) will just use 5 bytes if we store 'romharshan', if each char takes a byte. rest 10 bytes will be free.
Questions : 77	What is the functionality of md5 function in PHP?
Answer : 77	Calculate the md5 hash of a string. The hash is a 32-character hexadecimal number. I use it to generate keys which I use to identify users etc. If I add random no techniques to it the md5 generated now will be totally different for the same string I am using.
Questions : 78	How can I load data from a text file into a table?
Answer : 78	you can use LOAD DATA INFILE file_name; syntax to load data from a text file. but you have to make sure thata) data is delimited b) columns and data matched correctly
Questions : 79	How can we know the number of days between two given dates using MySQL?
Answer : 79	SELECT DATEDIFF("2007-03-07","2005-01-01");
Questions : 80	How can we know the number of days between two given dates using PHP?
Answer : 80	$date1 = date("Y-m-d"); $date2 = "2006-08-15"; $days = (strtotime($date1) - strtotime($date2)) / (60 * 60 * 24);
Questions : 81	How we load all classes that placed in different directory in one PHP File , means how to do auto load classes
Answer : 81	by using spl_autoload_register('autoloader::funtion'); Like below class autoloader { public static function moduleautoloader($class) { $path = $_SERVER['DOCUMENT_ROOT'] . "/modules/{$class}.php"; if (is_readable($path)) require $path; } public static function daoautoloader($class) { $path = $_SERVER['DOCUMENT_ROOT'] . "/dataobjects/{$class}.php"; if (is_readable($path)) require $path; } public static function includesautoloader($class) { $path = $_SERVER['DOCUMENT_ROOT'] . "/includes/{$class}.php"; if (is_readable($path)) require $path; } } spl_autoload_register('autoloader::includesautoloader'); spl_autoload_register('autoloader::daoautoloader'); spl_autoload_register('autoloader::moduleautoloader');
Questions : 82	How many types of Inheritances used in PHP and how we achieve it
Answer : 82	As far PHP concern it only support single Inheritance in scripting. we can also use interface to achieve multiple inheritance.
Questions : 83	PHP how to know user has read the email?
Answers : 83	Using Disposition-Notification-To: in mailheader we can get read receipt. Add the possibility to define a read receipt when sending an email. It’s quite straightforward, just edit email.php, and add this at vars definitions: var $readReceipt = null; And then, at ‘createHeader’ function add: if (!empty($this->readReceipt)) { $this->__header .= ‘Disposition-Notification-To: ‘ . $this->__formatAddress($this->readReceipt) . $this->_newLine; }
Questions : 84	What are default session time and path?
Answers : 84	default session time in PHP is 1440 seconds or 24 minutes Default session save path id temporary folder /tmp
Questions : 85	how to track user logged out or not? when user is idle ?
Answers : 85	By checking the session variable exist or not while loading th page. As the session will exist longer as till browser closes. The default behaviour for sessions is to keep a session open indefinitely and only to expire a session when the browser is closed. This behaviour can be changed in the php.ini file by altering the line session.cookie_lifetime = 0 to a value in seconds. If you wanted the session to finish in 5 minutes you would set this to session.cookie_lifetime = 300 and restart your httpd server.
Questions : 86	how to track no of user logged in ?
Answers : 86	whenever a user logs in track the IP, userID etc..and store it in a DB with a active flag while log out or sesion expire make it inactive. At any time by counting the no: of active records we can get the no: of visitors.
Questions : 87	in PHP for pdf which library used?
Answers : 87	The PDF functions in PHP can create PDF files using the PDFlib library With version 6, PDFlib offers an object-oriented API for PHP 5 in addition to the function-oriented API for PHP 4. There is also the » Panda module. FPDF is a PHP class which allows to generate PDF files with pure PHP, that is to say without using the PDFlib library. F from FPDF stands for Free: you may use it for any kind of usage and modify it to suit your needs. FPDF requires no extension (except zlib to activate compression and GD for GIF support) and works with PHP4 and PHP5.
Questions : 88	for image work which library?
Answers : 88	we will need to compile PHP with the GD library of image functions for this to work. GD and PHP may also require other libraries, depending on which image formats you want to work with.
Questions : 89	what is design pattern? singleton pattern?
Answers : 89	A design pattern is a general reusable solution to a commonly occurring problem in software design. The Singleton design pattern allows many parts of a program to share a single resource without having to work out the details of the sharing themselves.
Questions : 90	what are magic methods?
Answers : 90	Magic methods are the members functions that is available to all the instance of class Magic methods always starts with "__". Eg. __construct All magic methods needs to be declared as public To use magic method they should be defined within the class or program scope Various Magic Methods used in PHP 5 are: __construct() __destruct() __set() __get() __call() __toString() __sleep() __wakeup() __isset() __unset() __autoload() __clone()
Questions : 91	what is magic quotes?
Answers : 91	Magic Quotes is a process that automagically escapes ncoming data to the PHP script. It’s preferred to code with magic quotes off and to instead escape the data at runtime, as needed. This feature has been DEPRECATED as of PHP 5.3.0 and REMOVED as of PHP 6.0.0. Relying on this feature is highly discouraged.
Questions : 92	what is cross site scripting? SQL injection?
Answers : 92	Cross-site scripting (XSS) is a type of computer security vulnerability typically found in web applications which allow code injection by malicious web users into the web pages viewed by other users. Examples of such code include HTML code and client-side scripts. SQL injection is a code injection technique that exploits a security vulnerability occurring in the database layer of an application. The vulnerability is present when user input is either incorrectly filtered for string literal escape characters embedded in SQL statements or user input is not strongly typed and thereby unexpectedly executed
Questions : 93	what is URL rewriting?
Answers : 93	Using URL rewriting we can convert dynamic URl to static URL Static URLs are known to be better than Dynamic URLs because of a number of reasons 1. Static URLs typically Rank better in Search Engines. 2. Search Engines are known to index the content of dynamic pages a lot slower compared to static pages. 3. Static URLs are always more friendlier looking to the End Users. along with this we can use URL rewriting in adding variables [cookies] to the URL to handle the sessions.
Questions : 94	what is the major php security hole? how to avoid?
Answers : 94	1. Never include, require, or otherwise open a file with a filename based on user input, without thoroughly checking it first. 2. Be careful with eval() Placing user-inputted values into the eval() function can be extremely dangerous. You essentially give the malicious user the ability to execute any command he or she wishes! 3. Be careful when using register_globals = ON It was originally designed to make programming in PHP easier (and that it did), but misuse of it often led to security holes 4. Never run unescaped queries 5. For protected areas, use sessions or validate the login every time. 6. If you don’t want the file contents to be seen, give the file a .php extension.
Questions : 95	whether PHP supports Microsoft SQL server ?
Answers : 95	The SQL Server Driver for PHP v1.0 is designed to enable reliable, scalable integration with SQL Server for PHP applications deployed on the Windows platform. The Driver for PHP is a PHP 5 extension that allows the reading and writing of SQL Server data from within PHP scripts. using MSSQL or ODBC modules we can access Microsoft SQL server.
Questions : 96	what is MVC? why its been used?
Answers : 96	Model-view-controller (MVC) is an architectural pattern used in software engineering. Successful use of the pattern isolates business logic from user interface considerations, resulting in an application where it is easier to modify either the visual appearance of the application or the underlying business rules without affecting the other. In MVC, the model represents the information (the data) of the application; the view corresponds to elements of the user interface such as text, checkbox items, and so forth; and the controller manages the communication of data and the business rules used to manipulate the data to and from the model. WHY ITS NEEDED IS 1 Modular separation of function 2 Easier to maintain 3 View-Controller separation means: A — Tweaking design (HTML) without altering code B — Web design staff can modify UI without understanding code
Questions : 97	what is framework? how it works? what is advantage?
Answers : 97	In general, a framework is a real or conceptual structure intended to serve as a support or guide for the building of something that expands the structure into something useful. Advantages : Consistent Programming Model Direct Support for Security Simplified Development Efforts Easy Application Deployment and Maintenance
Questions : 98	what is CURL?
Answers : 98	CURL means Client URL Library curl is a command line tool for transferring files with URL syntax, supporting FTP, FTPS, HTTP, HTTPS, SCP, SFTP, TFTP, TELNET, DICT, LDAP, LDAPS and FILE. curl supports SSL certificates, HTTP POST, HTTP PUT, FTP uploading, HTTP form based upload, proxies, cookies, user+password authentication (Basic, Digest, NTLM, Negotiate, kerberos…), file transfer resume, proxy tunneling and a busload of other useful tricks. CURL allows you to connect and communicate to many different types of servers with many different types of protocols. libcurl currently supports the http, https, ftp, gopher, telnet, dict, file, and ldap protocols. libcurl also supports HTTPS certificates, HTTP POST, HTTP PUT, FTP uploading (this can also be done with PHP’s ftp extension), HTTP form based upload, proxies, cookies, and user+password authentication.
Questions : 99	what is PDO ?
Answers : 99	The PDO ( PHP Data Objects ) extension defines a lightweight, consistent interface for accessing databases in PHP. if you are using the PDO API, you could switch the database server you used, from say PgSQL to MySQL, and only need to make minor changes to your PHP code. While PDO has its advantages, such as a clean, simple, portable API but its maindisadvantage is that it doesn't allow you to use all of the advanced features that are available in the latest versions of MySQL server. For example, PDO does not allow you to use MySQL's support for Multiple Statements. Just need to use below code for connect mysql using PDO try { $dbh = new PDO("mysql:host=$hostname;dbname=databasename", $username, $password); $sql = "SELECT * FROM employee"; foreach ($dbh->query($sql) as $row) { print $row['employee_name'] .' - '. $row['employee_age'] ; } } catch(PDOException $e) { echo $e->getMessage(); }
Questions : 100	What is PHP's mysqli Extension?
Answers : 100	The mysqli extension, or as it is sometimes known, the MySQL improved extension, was developed to take advantage of new features found in MySQL systems versions 4.1.3 and newer. The mysqli extension is included with PHP versions 5 and later. The mysqli extension has a number of benefits, the key enhancements over the mysql extension being: =>Object-oriented interface =>Support for Prepared Statements =>Support for Multiple Statements =>Support for Transactions =>Enhanced debugging capabilities =>Embedded server support Versions ------------- Web developer suite 2.0 Apache server 2.2.6 Php 5.2.5 Mysql 5.0.45 Web application ----------------- Joomla 1.0.13 Drupal 5.3.0 WordPress 2.3.1 phpBB2 2.0.22 101. what is difference between <? ?>(short tag) and <?php ?>(full tag). 102. What does a special set of tags <?= and ?> do in PHP? ans- The output is displayed directly to the browser.It works like echo or print function. 103. what is difference between echo and print? ans- print returns the value in true or false, where as echo doesnot return anything. 104. what is difference between explode implode? ans-explode function:-it breaks a string into array. <?php $str="hello world.it's a beautiful day.": print_r(explode(" ",$str):// space between two double quotes should be there otherwise it shows Warning: explode() [function.explode]: Empty delimiter in D:\www\vhosts\localhost\test\setupTest.php on line 29 ?> ans-ARRAY [0]=>hello [1]=>world. [2]=>it's [3]=>a [4]=>beautiful [5]=>day. implode:-returns a string from elements of an array. <?php $arr=array('hello','world!',beautiful,'day!'); echo implode(" ",$arr); ?> ans-hello world! beautiful day! 105.Will comparison of string "10" and integer 11 work in PHP? ans-Yes, internally PHP will cast everything to the integer type, so numbers 10 and 11 will be compared. 106. how many types array are there in php? ans- There are two types of array- a) numerical or index array b) associative array     In numerical or index array the indexer,which is used to determine the position of a stored data (also known as key) is an integer.     Where as in case of associative array the indexer or key which is used to reffered the data element is a string. 107. what is terinary opertion in php? ans- It is called the ternary operator because it takes three operands - a condition, a result for true, and a result for false.                     OR Expression preceding the ? is evaluated, if it’s true, then the expression preceding    the : is executed, otherwise, the expression following : is executed.     <?php             $agestr = ($age < 18) ? 'child' : 'adult';     ?> 108. explain two types of arraay sort. ans-sort()->sort the array value alphabetically, but not maintaining the index.     asort()->sort the array value alphabetically, and also maintaining the index.     arsort()->sort the array value alphabetically in reverse order and also maintaining the index.     ksort()->sort the array according to key.     krsort()->sort the array according to key in the reverse order. 109. what is difference between strstr and stristr? strstr-finds the first occurence of a string inside another string (case-sensitive) examle: <?php $email = 'arvindpippal@gmail.com'; $domain = strstr($email, '@'); echo $domain; ?> output: @gmail.com stristr-finds the first occurence of a string inside another string (case-insensitive) 110.what is substr()? ans-substr() returns the portion of string specified by the start and length parameters. syntax:- string substr ( string string, int start [, int length] ) 111.Can u change localhost name in ur localsystem? ans- yes, inside     C:\Windows\System32\drivers\etc\hosts 112.how can u know size of array? ans-The sizeof() function counts the elements of an array, or the properties of an object. This function is an alias of the count() function. $a = array(1,2,2,     array(1,1));     echo sizeof($a);// 4     echo sizeof($a[1]);// 1         echo sizeof($a[3]);// 2 113.Number of argument in a function,How can u know? ans-func_num_args() function returns the number of parameters passed in. 114.what is a session and how can u destroy it? ans-A PHP session allowing you to store user information on the server for later use (i.e. username, shopping items, etc). However, session information is temporary and will be deleted after the user has left the website. If you need a permanent storage you may want to store the data in a database.     we are using session_unset()(deprecated) or session_destroy() to destroy the session. session_unset() free the all session variables,but session continues whereas session_destroy() destroys the session. 115.what is a cookies and how can u destroy it? ans-. A cookie is a small file that the server embeds on the user's computer. Each time the same computer requests a page with a browser, it will send the cookie too.     The setcookie() function is used to set a cookie.     <?php     $expire=time()+60*60*24*30;     setcookie("user", "Alex Porter", $expire);     ?> The PHP $_COOKIE variable is used to retrieve a cookie value.     <?php     // Print a cookie     echo $_COOKIE["user"];     // A way to view all cookies     print_r($_COOKIE);     ?> When deleting a cookie you should assure that the expiration date is in the past.     <?php     // set the expiration date to one hour ago     setcookie("user", "", time()-3600);     ?> 116. how can u get current date and time? ans- date('r'); 117. how can u upload a image? ans- we can upload a file by using the function move_uploaded_method() function. 18. what is difference between get and post? ans-GET:- get method is default method.     un secure way as data send through the url.     we can send limited amount of data as url supports 255 characters.     POST:- not a default method, we have to mention it explicitly.     its a secure way as data send through the body part.     we can send unlimited amount of data.     119. How can u et ip address of asystem? ans- $_SERVER['SERVER_ADDR'];      $_SERVER['REMOTE_ADDR']; 120. What is magic function and what are they? 121. What is Isset()? ans-isset() determines whether a certain variable has already been declared by PHP. It returns a boolean value true if the variable has already been set, and false otherwise, or if the variable is set to the value NULL. 122. How can you submit a form without using submit buttom? ans-Using javascript we can submit a form without using submmit button.                     OR If you don’t want to use the Submit button to submit a form, you can use normal hyper links to submit a form. But you need to use some JavaScript code in the URL of the link. For example: <a href=”javascript: document.myform.submit();”>Submit Me</a> 123. what is difference between require() and require_once()? ans-require() includes and evaluates a specific file while require_once() does that only if it has not been included before (on the same page). 124. what is difference between include() and include_once()? ans-include() includes and evaluates a specific file while include_once() does that only if it has not been included before (on the same page). 125. what is difference between include() and require()? ans- It’s how they handle failures. If the file is not found by require(), it will cause a fatal error and halt the execution of the script. If the file is not found by include(), a warning will be issued, but execution will continue. 126. What is the difference between ereg_replace() and eregi_replace()? ans-eregi_replace() function is identical to ereg_replace() except that it ignores case distinction when matching alphabetic characters. 127. what is oops? ans-One of the main advantages of OO programming is its ease of modification; objects can easily be modified and added to a system there by reducing maintenance costs. OO programming is also considered to be better at modeling the real world than is procedural programming. It allows for more complicated and flexible interactions. OO systems are also easier for non-technical personnel to understand and easier for them to participate in the maintenance and enhancement of a system because it appeals to natural human cognition patterns. For some systems, an OO approach can speed development time since many objects are standard across systems and can be reused. Components that manage dates, shipping, shopping carts, etc. can be purchased and easily modified for a specific system. 128. What in inheritance and how many types of inheritance are there in php? 129. What in methodoverloading and polymerphism? 130. What is methodoverriding? 131. What is method overloading and over riding? 132. What is Php encapsulation? 133. What is abstarct method and abstarct class? 134. What is final method and final class? 135. What is Super concepts? 136. What is constructor and destructor? 137. what are the access specifier? ans-The visibility of a property or method can be defined by prefixing the declaration with the keywords public, protected or private. Class members declared public can be accessed everywhere. Members declared protected can be accessed only within the class itself and by inherited and parent classes. Members declared as private may only be accessed by the class that defines the member. 138. What is 'This' key word? 139. what is coersion? 140. What is interface? 141. What is Exception handling? 142. waht is wrapper calss? 143. Give an example of Foreach; 144. what is split();? ans- split is a function used for split the string by regular expression.      split(":",$string); 145. What is abstraction in php? 146. function to display money separator by comma? 147. How can we send mail using JavaScript? ans-No. There is no way to send emails directly using JavaScript. But you can use JavaScript to execute a client side email program send the email using the “mailto” code. Here is an example: {xtypo_code} function myfunction(form) {    tdata=document.myform.tbox1.value;    location=”mailto: mailid@domain.com?subject=…”;    return true; } {/xtypo_code} 148.What is the difference between the functions unlink and unset? ans-unlink() is a function for file system handling. It will simply delete the file in context. unset() is a function for variable management. It will make a variable undefined. 149. what is difference between split() and explode()? ans- split()-split the string by regular expression.     split(":",$string);      explode()-split the string by string.     explode("",$string); 150. How can you get browser informaion in php? 151. what is difference between sinle qoute and double qoute? 152. what is role of == and === ,when we compare array? 153. what is CURL and its functionality? 154. what is MIME? ans-MIME is Multipurpose Internet Mail Extensions is an Internet standard for the format of e-mail. However browsers also uses MIME standard to transmit files. MIME has a header which is added to a beginning of the data. When browser sees such header it shows the data as it would be a file (for example image) Some examples of MIME types: audio/x-ms-wmp image/png aplication/x-shockwave-flash                         OR Multipurpose Internet Mail Extensions. WWW’s ability to recognize and handle files of different types is largely dependent on the use of the MIME (Multipurpose Internet Mail Extensions) standard. The standard provides for a system of registration of file types with information about the applications needed to process them. This information is incorporated into Web server and browser software, and enables the automatic recognition and display of registered file types. … 155. what is difference between drop table and truncate table? ans-DROP TABLE table_name – This will delete the table and its data. TRUNCATE TABLE table_name – This will delete the data of the table, but not the table definition. 156. what is difference between unset and unlink? 157. what is difference between __sleep and __wakeup()? ans-- __sleep returns the array of all the variables than need to be saved, while __wakeup retrieves them. 158. what is difference between htmlenties and htmlspecialcharacter()? ans- htmlspecialchars only takes care of <, >, single quote ‘, double quote ” and ampersand. htmlentities translates all occurrences of character sequences that have different meaning in HTML. 159. Whar are the errors in php? ans-Here are three basic types of runtime errors in PHP: 1. Notices: These are trivial, non-critical errors that PHP encounters while executing a script – for example, accessing a variable that has not yet been defined. By default, such errors are not displayed to the user at all – although you can change this default behavior. 2. Warnings: These are more serious errors – for example, attempting to include() a file which does not exist. By default, these errors are displayed to the user, but they do not result in script termination. 3. Fatal errors: These are critical errors – for example, instantiating an object of a non-existent class, or calling a non-existent function. These errors cause the immediate termination of the script, and PHP’s default behavior is to display them to the user when they take place. Internally, these variations are represented by twelve different error types 160. Is object of a class pass by a refference? ans- Everything is passed by value. 161. What are the differences between mysql_fetch_array(), mysql_fetch_object(), mysql_fetch_row()? ans-mysql_fetch_array – Fetch a result row as an associative array and a numeric array. mysql_fetch_object – Returns an object with properties that correspond to the fetched row and moves the internal data pointer ahead. Returns an object with properties that correspond to the fetched row, or FALSE if there are no more rows mysql_fetch_row() – Fetches one row of data from the result associated with the specified result identifier. The row is returned as an array. Each result column is stored in an array offset, starting at offset 0. 162. How can you know value of a current session id? ans-session_id(); 163. How can you find difference between two dates? 164. how can u encrypt user name or passwors in php? ans-using md5() we can encrypt username or password field in php. 165. How many way you can get a date from mysql? ans-SELECT CURDATE(); SELECT CURRENT_DATE(); SELECT CURTIME(); SELECT CURRENT_TIME(); 166. what is mysql engines and what are they? 167. what is difference between myisam and innodb? 168. what are the joins in mysql and what are they? ans-Different types of joins are ----     1.JOIN(Inner Join): Return rows when there is at least one match in both tables     2.LEFT JOIN: Return all rows from the left table, even if there are no matches in the right table     3.RIGHT JOIN: Return all rows from the right table, even if there are no matches in the left table     4.FULL JOIN: Return rows when there is a match in one of the tables 169. what is normalisation ? ans-The normalization process involves getting our data to conform to three progressive normal forms, and a higher level of normalization cannot be achieved until the previous levels have been achieved (there are actually five normal forms, but the last two are mainly academic and will not be discussed). First Normal Form The First Normal Form (or 1NF) involves removal of redundant data from horizontal rows. We want to ensure that there is no duplication of data in a given row, and that every column stores the least amount of information possible (making the field atomic). Second Normal Form Where the First Normal Form deals with redundancy of data across a horizontal row, Second Normal Form (or 2NF) deals with redundancy of data in vertical columns. As stated earlier, the normal forms are progressive, so to achieve Second Normal Form, your tables must already be in First Normal Form. Third Normal Form I have a confession to make; I do not often use Third Normal Form. In Third Normal Form we are looking for data in our tables that is not fully dependant on the primary key, but dependant on another value in the table 170. What is the maximum length of a table name, a database name, or a field name in MySQL? ans- Database name: 64 characters Table name: 64 characters Column name: 64 characters 171. list of php CMS?                                ans - Drupal, Joomla, PhpBB, Wordpress. 172. list of frameworks in php ? ans- Zend,CodeIgniter and CackePHP framework. 173. Difference between CMS and Framework. ans-An application framework is something which we use to build our web application on, I mean we use the framework provided classes, events, methods and create an application. A CMS is already a developed application with a set of features, however most of them are coded in such a way that users can tweak them around and modify the code to fit their own needs. So a framework does not come with a working application, but a CMS comes with one. 174. Http default port no.? ans- 80 175. Http is stateless or stateful? ans- stateless. 176. How to unset coockie? ans- by setting the set cookie method in back date.     setcookie(name,value,expire,path,domain,secure)     setcookie("TestCookie",$value, time()+3600*24);     setcookie ("TestCookie", "", time() - 3600); 177. what is the output ?     <?php         $param = "value";         $value = 10;         print ${$param};// 10         print $$param;// 10         print '$$param';// $$param     ?> 178. What is the function to upload a file? ans - move_uploaded_file(); 179. Max execution time? ans- 30sec. 180. Max uploading size? ans- 2Mb 181. How session starts? ans- session_start() 82.What is ob_start()? ans-ob_start() function turn on the output buffering, while output buffering is active no output is sent from the script, other than header. 183. how to run php file from command prompt? 184. Difference between session and cookie? 185. What is stored procedure? 186. What is the use of === ? 187. Use of static keyword? ans-Declaring class properties or methods as static makes them accessible without needing an instantiation of the class. 188. Types of file format under mysql5->data folder? ans- There are three types of file format     1.frm     2.MYD     3.MYI 189. What are the new features added in PHP5 ? ans- Addition features of PHP5-----     1.Visibility     2.Abstract     3.Final     4.Methods     5.Class     6.Magic methods or functions     7.Interface     8.Cloning     9.Typehinting 190. What is AJAX ? ans-AJAX = Asynchronous JavaScript and XML. AJAX is a technique for creating fast and dynamic web pages. AJAX allows web pages to be updated asynchronously by exchanging small amounts of data with the server behind the scenes. This means that it is possible to update parts of a web page, without reloading the whole page. AJAX applications are browser- and platform-independent! All modern browsers support the XMLHttpRequest object (IE5 and IE6 uses an ActiveXObject). The XMLHttpRequest object is used to exchange data with a server behind the scenes. This means that it is possible to update parts of a web page, without reloading the whole page. var xmlhttp; if (window.XMLHttpRequest)   {// code for IE7+, Firefox, Chrome, Opera, Safari   xmlhttp=new XMLHttpRequest();   } else   {// code for IE6, IE5   xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");   } To handle all modern browsers, including IE5 and IE6, check if the browser supports the XMLHttpRequest object. If it does, create an XMLHttpRequest object, if not, create an ActiveXObject To send a request to a server, we use the open() and send() methods of the XMLHttpRequest object: xmlhttp.open("GET","ajax_info.txt",true); xmlhttp.send(); GET is simpler and faster than POST, and can be used in most cases. However, always use POST requests when:     * A cached file is not an option (update a file or database on the server)     * Sending a large amount of data to the server (POST has no size limitations)     * Sending user input (which can contain unknown characters), POST is more robust and secure than GET If you want to send information with the GET method, add the information to the URL: xmlhttp.open("GET","demo_get2.asp?fname=Henry&lname=Ford",true); xmlhttp.send(); To POST data like an HTML form, add an HTTP header with setRequestHeader(). Specify the data you want to send in the send() method: xmlhttp.open("POST","ajax_test.asp",true); xmlhttp.setRequestHeader("Content-type","application/x-www-form-urlencoded"); xmlhttp.send("fname=Henry&lname=Ford"); setRequestHeader(header,value) ->Adds HTTP headers to the request. header: specifies the header name value: specifies the header value AJAX stands for Asynchronous JavaScript and XML, and for the XMLHttpRequest object to behave as AJAX, the async parameter of the open() method has to be set to true: xmlhttp.open("GET","ajax_test.asp",true); Sending asynchronously requests is a huge improvement for web developers. Many of the tasks performed on the server are very time consuming. Before AJAX, this operation could cause the application to hang or stop. With AJAX, the JavaScript does not have to wait for the server response, but can instead:     * execute other scripts while waiting for server response     * deal with the response when the response ready Async=true When using async=true, specify a function to execute when the response is ready in the onreadystatechange event: xmlhttp.onreadystatechange=function()   {   if (xmlhttp.readyState==4 && xmlhttp.status==200)     {     document.getElementById("myDiv").innerHTML=xmlhttp.responseText;     }   } xmlhttp.open("GET","ajax_info.txt",true); xmlhttp.send(); Async=false To use async=false, change the third parameter in the open() method to false: Using async=false is not recommended, but for a few small requests this can be ok. Remember that the JavaScript will NOT continue to execute, until the server response is ready. If the server is busy or slow, the application will hang or stop. Note: When you use async=false, do NOT write an onreadystatechange function - just put the code after the send() statement: xmlhttp.open("GET","ajax_info.txt",false); xmlhttp.send(); document.getElementById("myDiv").innerHTML=xmlhttp.responseText; The onreadystatechange event ------------------------------- When a request to a server is sent, we want to perform some actions based on the response. The onreadystatechange event is triggered every time the readyState changes. The readyState property holds the status of the XMLHttpRequest. Three important properties of the XMLHttpRequest object: In the onreadystatechange event, we specify what will happen when the server response is ready to be processed. When readyState is 4 and status is 200, the response is ready: xmlhttp.onreadystatechange=function()   {   if (xmlhttp.readyState==4 && xmlhttp.status==200)     {     document.getElementById("myDiv").innerHTML=xmlhttp.responseText;     }   } if (window.XMLHttpRequest)   {// code for IE7+, Firefox, Chrome, Opera, Safari   xmlhttp=new XMLHttpRequest();   } else   {// code for IE6, IE5   xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");   } xmlhttp.onreadystatechange=function()   {   if (xmlhttp.readyState==4 && xmlhttp.status==200)     {     document.getElementById("txtHint").innerHTML=xmlhttp.responseText;     }   } xmlhttp.open("GET","gethint.php?q="+str,true); xmlhttp.send(); 91. What is main strength of Ajax ? ans- AJAX does not refresh or reload the whole page as because Ajax uses asynchronous technology. In a word, a program does not wait for response after requesting an asynchronous call whereas synchronous does so. 192. How session works? ans- Nearly every PHP application uses sessions. This article takes a detailed look at implementing a secure session management mechanism with PHP. Following a fundamental introduction to HTTP, the challenge of maintaining state, and the basic operation of cookies, I will step through simple and effective methods that can be used to increase the security and reliability of your stateful PHP applications. It is a common misconception that PHP provides a certain level of security with its native session management features. On the contrary, PHP simply provides a convenient mechanism. It is up to the developer to provide the complete solution, and as you will see, there is no one solution that is best for everyone. Statelessness HTTP is a stateless protocol. This is because there is nothing within the protocol that requires the browser to identify itself during each request, and there is also no established connection between the browser and the web server that persists from one page to the next. When a user visits a web site, the user's browser sends an HTTP request to the web server, which in turn sends an HTTP response in reply. This is the extent of the communication, and it represents a complete HTTP transaction. Because the web relies on HTTP for communication, maintaining state in a web application can be particularly challenging for developers. Cookies are an extension of HTTP that were introduced to help provide stateful HTTP transactions, but privacy concerns have prompted many users to disable support for cookies. State information can be passed in the URL, but accidental disclosure of this information poses serious security risks. In fact, the very nature of maintaining state requires that the client identify itself, yet the security-conscious among us know that we should never trust information sent by the client. Despite all of this, there are elegant solutions to the problem of maintaining state. There is no perfect solution, of course, nor is there one solution that can satisfy everyone's needs. This article introduces some techniques that can reliably provide statefulness as well as defend against session-based attacks such as session hijacking. Along the way, you will learn how cookies really work, what PHP sessions do, and what is required to hijack a session. 193.What is interface? ans- PHP does not support multiple inheritance directly, to implement this we need Interface. It is much similar to Interface of Java. In PHP, signature of the method are declared in the Interface body, and the body part of the method is implemented in derived class. Variables are declared as constant and it can not be changed in the child classes. We use implement keyword to extend this kind of class, at the same time we can implement more than one interface and one interface can be implemented by another interface. All methods declared in an interface must be public and the variables should be constant. This is mandatory that we must declare the body part of the method in the derived class otherwise an error message will be generated. Example: <?php interface Inter{ const a="This is constant value"; public function disp(); } class A implements Inter{ function show(){ echo self::a."<br/>";} public function disp(){ echo "Inside the disp function";}} $a=new A(); $a->show(); $a->disp(); ?> Output: This is constant value Inside the disp function 194. Difference between Http and Ftp ? ans- 1 FTP stands for File Transfer Protocol. HTTP stands for Hyper Text Transfer Protocol 2 FTP, is a protocol used to upload files from a workstation to a FTP server or download files from a FTP server to a workstation. HTTP, is a protocol used to transfer files from a Web server onto a browser in order to view a Web page that is on the Internet. 3 When ftp appears in a URL it means that the user is connecting to a file server and not a Web server and that some form of file transfer is going to take place. When http appears in a URL it means that the user is connecting to a Web server and not a file server. The files are transferred but not downloaded, therefore not copied into the memory of the receiving device. 4 FTP is a two-way system as files are transferred back and forth between server and workstation. HTTP is a one-way system as files are transported only from the server onto the workstation's browser. 5 FTP, where entire files are transferred from one device to another and copied into memory, HTTP only transfers the contents of a web page into a browser for viewing. 6 FTP file uploaded is used in cases when the file size is more than 70 MB HTTP upload is used for smaller files. 7 FTP uses an FTP client server and an FTP client. HTTP is used for all web [ages i.e. it is the standard protocol to transmit hyperlinked documents and files. It is often used in conjunction with HTML. 8 FTP was the original non-GUI file transfer program and could be run from a command line interface like MS-DOS. HTTP is associated with a browser file transfer program like Internet Explorer.