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十三、MariaDB 删除查询

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DELETE命令从指定的表中删除表行,并返回已删除的数量。 访问使用ROW_COUNT()函数删除的数量。 WHERE子句指定行,如果没有行,则删除所有行。 LIMIT子句控制删除的行数。

在多行的DELETE语句中,它只删除满足条件的那些行; 并且不允许LIMIT和WHERE子句。 DELETE语句允许从不同数据库中的表中删除行,但不允许从表中删除,然后从子查询中的同一个表中进行选择。

查看以下DELETE语法 –

DELETE FROM table_name [WHERE …]

从命令提示符或使用PHP脚本执行DELETE命令。

命令提示符

在命令提示符下,只需使用标准命令 –

root@host# mysql –u root –p password;
Enter password:*******
mysql> use PRODUCTS;
Database changed
mysql> DELETE FROM products_tbl WHERE product_id=133;
mysql> SELECT * from products_tbl WHERE ID_number='133';
ERROR 1032 (HY000): Can't find record in 'products_tbl'

PHP删除查询脚本

在DELETE命令语句中使用mysql_query()函数 –

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

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

   $sql = 'DELETE FROM products_tbl WHERE product_id = 261';
   mysql_select_db('PRODUCTS');
   $retval = mysql_query( $sql, $conn );

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

   echo "Deleted data successfully
";
   mysql_close($conn);
?>

成功删除数据后,您将看到以下输出 –

mysql> Deleted data successfully
mysql> SELECT * from products_tbl WHERE ID_number='261';
ERROR 1032 (HY000): Can't find record in 'products_tbl'


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