MySQL UPDATE query

If we need to modify or update the data in MySQL, we can use SQL UPDATE command to operate. .

grammar

The following is the UPDATE command to modify the MySQL Data Sheet Data General SQL syntax:

UPDATE table_name SET field1=new-value1, field2=new-value2
[WHERE Clause]

• You can update one or more fields simultaneously.
• You can specify any condition in the WHERE clause.
• You can also update the data in a separate table.

When you need to update the data specified in the table rows WHERE clause is very useful.

Below we will update w3big_tbl specified in the table data using SQL UPDATE command WHERE clause:

Examples

The following example will update the data table as w3big_title w3big_id field value 3:

root@host# mysql -u root -p password;
Enter password:*******
mysql> use w3big;
Database changed
mysql> UPDATE w3big_tbl 
    -> SET w3big_title='Learning JAVA' 
    -> WHERE w3big_id=3;
Query OK, 1 row affected (0.04 sec)
Rows matched: 1  Changed: 1  Warnings: 0

mysql>

Use PHP script to update data

PHP function for use mysql_query () to execute SQL statements, you can use SQL UPDATE statement or WHERE clause does not apply.

This function is in the mysql> command prompt effect executing SQL statements is the same.

Examples

The following example will update w3big_id data w3big_title field 3.

<?php
$dbhost = 'localhost:3036';
$dbuser = 'root';
$dbpass = 'rootpassword';
$conn = mysql_connect($dbhost, $dbuser, $dbpass);
if(! $conn )
{
  die('Could not connect: ' . mysql_error());
}
$sql = 'UPDATE w3big_tbl
        SET w3big_title="Learning JAVA"
        WHERE w3big_id=3';

mysql_select_db('w3big');
$retval = mysql_query( $sql, $conn );
if(! $retval )
{
  die('Could not update data: ' . mysql_error());
}
echo "Updated data successfully\n";
mysql_close($conn);
?>