PHP MySQL DELETE 查询

在本教程中，你将学习如何使用 PHP 从 MySQL 表中删除记录。

删除数据库表数据

就像将记录插入表中一样，你可以使用 SQL DELETE 语句从表中删除记录。它通常与子句 WHERE 一起使用，仅删除那些符合特定条件或条件的记录。

DELETE 语句的基本语法如下：

DELETE FROM table_name WHERE column_name=some_value 

让我们使用 DELETE 语句和 WHERE 子句进行 SQL 查询，然后我们将执行此查询，方法是将其传递给 PHP mysqli_query() 函数以删除表记录。考虑 demo 数据库中的 persons 表 ：

+----+------------+-----------+----------------------+
| id | first_name | last_name | email                |
+----+------------+-----------+----------------------+
|  1 | Peter      | Parker    | peterparker@mail.com |
|  2 | John       | Rambo     | johnrambo@mail.com   |
|  3 | Clark      | Kent      | clarkkent@mail.com   |
|  4 | John       | Carter    | johncarter@mail.com  |
|  5 | Harry      | Potter    | harrypotter@mail.com |
+----+------------+-----------+----------------------+

以下示例中的 PHP 代码将从 person 表中删除 first_name 等于 John 的这些人的记录。

面向过程方式

<?php
/* Attempt MySQL server connection. Assuming you are running MySQL
server with default setting (user 'root' with no password) */
$link = mysqli_connect("localhost", "root", "", "demo");
 
// Check connection
if($link === false){
    die("ERROR: Could not connect. " . mysqli_connect_error());
}
 
// Attempt delete query execution
$sql = "DELETE FROM persons WHERE first_name='John'";
if(mysqli_query($link, $sql)){
    echo "Records were deleted successfully.";
} else{
    echo "ERROR: Could not able to execute $sql. " . mysqli_error($link);
}
 
// Close connection
mysqli_close($link);
?>

面向过程方式

<?php
/* Attempt MySQL server connection. Assuming you are running MySQL
server with default setting (user 'root' with no password) */
$mysqli = new mysqli("localhost", "root", "", "demo");
 
// Check connection
if($mysqli === false){
    die("ERROR: Could not connect. " . $mysqli->connect_error);
}
 
// Attempt delete query execution
$sql = "DELETE FROM persons WHERE first_name='John'";
if($mysqli->query($sql) === true){
    echo "Records were deleted successfully.";
} else{
    echo "ERROR: Could not able to execute $sql. " . $mysqli->error;
}
 
// Close connection
$mysqli->close();
?>

PDO 方式

<?php
/* Attempt MySQL server connection. Assuming you are running MySQL
server with default setting (user 'root' with no password) */
try{
    $pdo = new PDO("mysql:host=localhost;dbname=demo", "root", "");
    // Set the PDO error mode to exception
    $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
} catch(PDOException $e){
    die("ERROR: Could not connect. " . $e->getMessage());
}
 
// Attempt update query execution
try{
    $sql = "DELETE FROM persons WHERE first_name='John'";  
    $pdo->exec($sql);
    echo "Records were deleted successfully.";
} catch(PDOException $e){
    die("ERROR: Could not able to execute $sql. " . $e->getMessage());
}
 
// Close connection
unset($pdo);
?>

删除后，persons 表将如下所示：

+----+------------+-----------+----------------------+
| id | first_name | last_name | email                |
+----+------------+-----------+----------------------+
|  1 | Peter      | Parker    | peterparker@mail.com |
|  3 | Clark      | Kent      | clarkkent@mail.com   |
|  5 | Harry      | Potter    | harrypotter@mail.com |
+----+------------+-----------+----------------------+

如你所见，记录已从人员表中成功删除。

警告： 在 DELETE 语句中的 WHERE 子句指定一个或多个记录应予删除。如果省略该 WHERE 子句，则将删除所有记录。