Updating data in MySQL

UPDATE statement is used to modify any field value in MySQL table.

Syntax:

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

one or more field altogether can be updated. WHERE clause can be used to specify any condition.

Here is an example 

Here is how we can do the example same thing using a PHP sccript

<?php
$server = "localhost";
$user = "username";
$pwd = "password";

try {
      $connection = new PDO("mysql:host=$server;dbname=testDB", $user, $pwd);
      $connection->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
      $sql = "UPDATE book_tbl set book_title='Learn C++ **' where book_id=2;";    
      $select->execute($sql);        
      echo "Book title for Book ID 2 updated.";
    }
    catch(PDOException $e)
    {
    echo "Connection failed: " . $e->getMessage();
    } 

?>

Database user must have Update_priv to update data else an exception will be thrown.

For more details on UPDATE statement, please read MySQL docs here

Delete data in MySQL

DELETE command is used to modify any field value in MySQL table. For detailed documentation please read here 

Syntax:

DELETE FROM table_name [WHERE Clause]

If there is no WHERE clause specified, then all records will be deleted.

To delete selected record need to specify the condition in WHERE clause.

Here is an example screenshot showing DELETE statement in action

From a PHP script here is how you can delete a row or multiple rows together.

<?php
$server = "localhost";
$user = "username";
$pwd = "password";

try {
      $connection = new PDO("mysql:host=$server;dbname=testDB", $user, $pwd);
      $connection->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
      $sql = "DELETE FROM book_tbl where book_id=2;";    
      $select->execute($sql);        
      echo "Book title for Book ID 2 deleted.";
    }
    catch(PDOException $e)
    {
    echo "Connection failed: " . $e->getMessage();
    } 

?>

In the next part of this tutorial, we will explore LIKE condition that is used in WHERE clause.