How to modify data in multiple tables in PHP

PHP is a popular programming language that can be used with a variety of database management systems. When we need to modify data in multiple tables, using PHP can greatly simplify the process. This article will introduce how to modify the data of multiple tables in PHP.

1. Connect to the database

First, we need to connect to the database in the PHP code. Assuming we are using a MySQL database, we can use the following code to connect to the database:

<?php $servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";

// 创建连接
$conn = mysqli_connect($servername, $username, $password, $dbname);

// 检查连接
if (!$conn) {
    die("连接失败: " . mysqli_connect_error());
}
echo "连接成功";
?>

2. Preparing SQL query statements

Next, we need to prepare the SQL query to be executed statement. Suppose we want to modify data in two tables, such as the user table and the orders table. We can use the following SQL statement:

UPDATE users, orders
SET users.name = 'New Name', orders.price = 50
WHERE users.id = 1 AND orders.user_id = 1;

This SQL statement will modify the name and price fields of the qualified data in the users table and orders table to "New Name" and 50.

3. Execute SQL query statement

Once we have prepared the SQL query statement, we can execute it in the PHP code. We can use the mysqli_query function to execute the query statement, as shown below:

$sql = "UPDATE users, orders SET users.name = 'New Name', orders.price = 50 WHERE users.id = 1 AND orders.user_id = 1";
if (mysqli_query($conn, $sql)) {
    echo "数据已更新";
} else {
    echo "更新数据时出错: " . mysqli_error($conn);
}

This code block will execute our prepared SQL query statement and output the corresponding information.

4. Full PHP code

The following is the complete PHP code for modifying data in multiple tables:

<?php $servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";

// 创建连接
$conn = mysqli_connect($servername, $username, $password, $dbname);

// 检查连接
if (!$conn) {
    die("连接失败: " . mysqli_connect_error());
}
echo "连接成功";

// 准备SQL查询语句
$sql = "UPDATE users, orders SET users.name = &#39;New Name&#39;, orders.price = 50 WHERE users.id = 1 AND orders.user_id = 1";

// 执行SQL查询语句
if (mysqli_query($conn, $sql)) {
    echo "数据已更新";
} else {
    echo "更新数据时出错: " . mysqli_error($conn);
}

// 关闭连接
mysqli_close($conn);
?>

5. Summary

Modifying data in multiple tables in PHP requires the following steps:

• Connect to the database
• Prepare SQL query statements
• Execute SQL query statement
• Close the connection

The above steps can simplify the operation and allow us to easily modify data in multiple tables.

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