How to modify a row of table data in php

PHP is a programming language widely used for developing web applications. In website development, we often need to add, delete, modify and check data in the database. Among them, modifying data is a frequently used operation. This article will introduce in detail how to use PHP to modify a row of table data.

1. Connect to the database

In PHP, connecting to the database is very simple. You only need to use PHP's built-in mysqli class. The following is a code example for connecting to a MySQL database:

<?php //数据库连接信息
$host = "localhost";
$username = "root";
$password = "123456";
$dbname = "test";
//创建连接
$conn = new mysqli($host, $username, $password, $dbname);
//检测连接
if ($conn->connect_error) {
    die("连接失败: " . $conn->connect_error);
}
echo "连接成功";
?>

2. Query the data to be modified

Usually, we need to first find the data to be modified through query operations. The following is a code example for querying data:

<?php //查询语句
$sql = "SELECT id, name, age FROM user WHERE id = 1";
$result = $conn->query($sql);
//检测查询结果是否为空
if ($result->num_rows > 0) {
    //输出数据
    while($row = $result->fetch_assoc()) {
        echo "id: " . $row["id"]. " - Name: " . $row["name"]. " - Age: " . $row["age"]. "<br>";
    }
} else {
    echo "0 结果";
}
$conn->close();
?>

3. Modify data

After obtaining the data to be modified, we can use the UPDATE statement to modify the data. The following is a code example for modifying data:

<?php //更新数据的语句
$sql = "UPDATE user SET name='Tom', age=25 WHERE id=1";
if ($conn->query($sql) === TRUE) {
    echo "数据更新成功";
} else {
    echo "数据更新失败: " . $conn->error;
}
$conn->close();
?>

In the above code, we use the UPDATE statement to update the user data with id 1. In the UPDATE statement, we can use the SET clause to specify the fields and values ​​to be modified, and the WHERE clause to specify the rows to be modified.

4. Complete code example

<?php //数据库连接信息
$host = "localhost";
$username = "root";
$password = "123456";
$dbname = "test";
//创建连接
$conn = new mysqli($host, $username, $password, $dbname);
//检测连接
if ($conn->connect_error) {
    die("连接失败: " . $conn->connect_error);
}

//查询语句
$sql = "SELECT id, name, age FROM user WHERE id = 1";
$result = $conn->query($sql);
//检测查询结果是否为空
if ($result->num_rows > 0) {
    //输出数据
    while($row = $result->fetch_assoc()) {
        echo "id: " . $row["id"]. " - Name: " . $row["name"]. " - Age: " . $row["age"]. "<br>";
    }
} else {
    echo "0 结果";
}

//更新数据的语句
$sql = "UPDATE user SET name='Tom', age=25 WHERE id=1";
if ($conn->query($sql) === TRUE) {
    echo "数据更新成功";
} else {
    echo "数据更新失败: " . $conn->error;
}

$conn->close();
?>

The above code completely demonstrates how to use PHP to modify a row of table data by connecting to the database, querying data and modifying data. Developers can modify parameters such as table names, field names, and query conditions in the code according to their own needs to implement corresponding functions.

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