MYSQL Delete Query

 If you want to delete a record from any MySQL table, then you can use the SQL command DELETE FROM. You can use this command at the mysql> prompt as well as in any script like PHP.

Syntax

The following code block has a generic SQL syntax of the DELETE command to delete data from a MySQL table.

DELETE FROM table_name [WHERE Clause]

• If the WHERE clause is not specified, then all the records will be deleted from the given MySQL table.
• You can specify any condition using the WHERE clause.
• You can delete records in a single table at a time.

The WHERE clause is very useful when you want to delete selected rows in a table.

Deleting Data Using a PHP Script

You can use the SQL DELETE command with or without the WHERE CLAUSE into the PHP function – mysql_query(). This function will execute the SQL command in the same way as it is executed at the mysql> prompt.

Example

Try the following example to delete a record from the tutorial_tbl whose tutorial_id is 3.

<?php
   $dbhost = 'localhost';
   $dbuser = 'root';
   $dbpass = '';
   $conn = mysql_connect($dbhost, $dbuser, $dbpass);
   
   if(! $conn ) {
      die('Could not connect: ' . mysql_error());
   }

   $sql = 'DELETE FROM tutorials_tbl WHERE tutorial_id = 3';

   mysql_select_db('TUTORIALS');
   $retval = mysql_query( $sql, $conn );

   if(! $retval ) {
      die('Could not delete data: ' . mysql_error());
   }
   echo "Deleted data successfully\n";
   mysql_close($conn);
?>

Delete Record From Datatbase Using MYSQL

 The SQL DELETE command is used to delete rows that are no longer required from the database tables. It deletes the whole row from the table. Delete command comes in handy to delete temporary or obsolete data from your database.The DELETE command can delete more than one row from a table in a single query. This proves to be advantages when removing large numbers of rows from a database table.

 Once a row has been deleted, it cannot be recovered. It is therefore strongly recommended to make database backups before deleting any data from the database. This can allow you to restore the database and view the data later on should it be required.

Syntax

The following code block has a generic SQL syntax of the DELETE command to delete data from a MySQL table.

DELETE FROM table_name [WHERE Clause]

• If the WHERE clause is not specified, then all the records will be deleted from the given MySQL table.
• You can specify any condition using the WHERE clause.
• You can delete records in a single table at a time.

The WHERE clause is very useful when you want to delete selected rows in a table.

Deleting Data from the Command Prompt

This will use the SQL DELETE command with the WHERE clause to delete selected data into the MySQL table – tutorials_tbl.

Example

The following example will delete a record from the tutorial_tbl whose tutorial_id is 3.

root@host# mysql -u root -p password;
Enter password:*******

mysql> use TUTORIALS;
Database changed

mysql> DELETE FROM tutorials_tbl WHERE tutorial_id=3;
Query OK, 1 row affected (0.23 sec)

mysql>

Deleting Data Using a PHP Script

You can use the SQL DELETE command with or without the WHERE CLAUSE into the PHP function – mysql_query(). This function will execute the SQL command in the same way as it is executed at the mysql> prompt.

Example

Try the following example to delete a record from the tutorial_tbl whose tutorial_id is 3.

<?php
   $dbhost = 'localhost';
   $dbuser = 'root';
   $dbpass = '';
   $conn = mysql_connect($dbhost, $dbuser, $dbpass);
   
   if(! $conn ) {
      die('Could not connect: ' . mysql_error());
   }

   $sql = 'DELETE FROM tutorials_tbl WHERE tutorial_id = 3';

   mysql_select_db('TUTORIALS');
   $retval = mysql_query( $sql, $conn );

   if(! $retval ) {
      die('Could not delete data: ' . mysql_error());
   }
   echo "Deleted data successfully\n";
   mysql_close($conn);
?>

What PHP is?

 

PHP stands for Hypertext Preprocessor. PHP is a powerful and widely-used open source server-side scripting language to write dynamically generated web pages. PHP scripts are executed on the server and the result is sent to the browser as plain HTML.

 PHP can be integrated with the number of popular databases, including MySQL, PostgreSQL, Oracle, Sybase, Informix, and Microsoft SQL Server.

PHP can be embedded within a normal HTML web pages. That means inside your HTML documents you'll have PHP statements like this:



Example:

<!DOCTYPE HTML>
<html>
<head>
    <title>PHP Application</title>
</head>
<body>
<?php
// Display greeting message
echo 'Hello World!';
?>
</body>
</html>

 What You Can Do with PHP 

There are lot more things you can do with PHP. 

•  You can generate dynamic pages and files. 
• You can create, open, read, write and close files on the server. 
• You can collect data from a web form such as user information, email, credit card information and much more. 
• You can send emails to the users of your website. 
• You can send and receive cookies to track the visitor of your website.
•  You can store, delete, and modify information in your database. 
• You can restrict unauthorized access to your website. 
• You can encrypt data for safe transmission over internet.