9. Learn MySQL delete statement

 MySQL DELETE sentence

You can use SQL Of DELETE FROM Command to delete MySQL Records in the data table .

You can  mysql>  Command prompt or PHP Execute the command in the script .

grammar

Here are SQL DELETE Statements from MySQL General syntax for deleting data from a data table ：

DELETE FROM table_name [WHERE Clause]

• If not specified WHERE Clause ,MySQL All records in the table will be deleted .
• You can WHERE Clause to specify any condition
• You can delete records once in a single table .

When you want to delete the record specified in the data table WHERE Clause is very useful .

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Delete data from the command line

So here we're going to be SQL DELETE Use in command WHERE Clause to delete MySQL Data sheet xxxxxx_tbl Selected data .  Friends who need the framework source code can see my personal profile and contact me .

example

The following examples will be deleted xxxxxx_tbl In the table xxxxxx_id by 3 The record of ：

DELETE sentence ：

mysql> use XXXXXX;
Database changed
mysql> DELETE FROM xxxxxx_tbl WHERE xxxxxx_id=3;
Query OK, 1 row affected (0.23 sec)

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Use PHP Script delete data

PHP Use mysqli_query() Function to execute SQL sentence , You can SQL DELETE Command with or without WHERE Clause .

The function and  mysql>  Command execution SQL The effect of the command is the same .

example

following PHP Instance will be deleted xxxxxx_tbl In the table xxxxxx_id by 3 The record of :

MySQL DELETE Clause test ：

<?php
$dbhost = 'localhost';  // mysql Server host address 
$dbuser = 'root';            // mysql user name 
$dbpass = '123456';          // mysql User name, password 
$conn = mysqli_connect($dbhost, $dbuser, $dbpass);
if(! $conn )
{
    die(' The connection fails : ' . mysqli_error($conn));
}
//  Set encoding , Prevent Chinese miscoding 
mysqli_query($conn , "set names utf8");
 
$sql = 'DELETE FROM xxxxxx_tbl
        WHERE xxxxxx_id=3';
 
mysqli_select_db( $conn, 'XXXXXXX' );
$retval = mysqli_query( $conn, $sql );
if(! $retval )
{
    die(' Unable to delete data : ' . mysqli_error($conn));
}
echo ' Data deletion successful ！';
mysqli_close($conn);
?>