The UPDATE command modifies existing fields by changing values. It uses the SET clause to specify columns for modification, and to specify the new values assigned. These values can be either an expression or the default value of the field. Setting a default value requires using the DEFAULT keyword. The command can also employ a WHERE clause to specify conditions for an update and/or an ORDER BY clause to update in a certain order.

Review the following general syntax −

UPDATE table_name SET field=new_value, field2=new_value2,...
[WHERE ...]

Execute an UPDATE command from either the command prompt or using a PHP script.

The Command Prompt

At the command prompt, simply use a standard commandroot −

root@host# mysql -u root -p password;
Enter password:*******
mysql> use PRODUCTS;
Database changed
mysql> UPDATE products_tbl
   SET nomenclature = ''Fiber Blaster 300Z'' WHERE ID_number = 112;
mysql> SELECT * from products_tbl WHERE ID_number=''112
+-------------+---------------------+----------------------+
| ID_number   | Nomenclature        | product_manufacturer |
+-------------+---------------------+----------------------+
| 112         | Fiber Blaster 300Z  | XYZ Corp             |
+-------------+---------------------+----------------------+      

PHP Update Query Script

Employ the mysql_query() function in UPDATE command statements −

<?php
   $dbhost = ‘localhost:3036’;
   $dbuser = ‘root’;
   $dbpass = ‘rootpassword’;
   $conn = mysql_connect($dbhost, $dbuser, $dbpass);

   if(! $conn ) {
      die(‘Could not connect: ‘ . mysql_error());
   }

   $sql = ‘UPDATE products_tbl
      SET product_name = ”Fiber Blaster 300z”
      WHERE product_id = 112’;

   mysql_select_db(‘PRODUCTS’);
   $retval = mysql_query( $sql, $conn );

   if(! $retval ) {
      die(‘Could not update data: ‘ . mysql_error());
   }

   echo “Updated data successfullyn”;
   mysql_close($conn);
?>

On successful data update, you will see the following output −

mysql> Updated data successfully