php change mysql data

PHP (Hypertext Preprocessor) is an open source, cross-platform scripting language that is widely used in the field of Web development. MYSQL is a popular relational database management system. In web development, PHP and MYSQL are usually used together to implement various functions of the website.

In PHP, we can use the function library provided by MYSQL to connect, query and modify data in the database. The following are some basic usage methods:

Connect to MYSQL database

In PHP, we can use the mysqli_connect() function to connect to the MYSQL database, as shown below:

$servername = "localhost";
$username = "root";
$password = "123456";
$dbname = "myDB";

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

// 检查连接是否成功
if (!$conn) {
    die("Connection failed: " . mysqli_connect_error());
}

Execute SQL statements and get results

In PHP, we can use the mysqli_query() function to execute SQL statements, as shown below:

$sql = "SELECT * FROM myTable";
$result = mysqli_query($conn, $sql);

if (mysqli_num_rows($result) > 0) {
    // 输出数据
    while($row = mysqli_fetch_assoc($result)) {
        echo "id: " . $row["id"]. " - Name: " . $row["name"]. " - Age: " . $row["age"]. "<br>";
    }
} else {
    echo "0 results";
}

Modify the data in the MYSQL database

In PHP, we can use the mysqli_query() function to execute the UPDATE statement, as shown below:

$sql = "UPDATE myTable SET name='Peter' WHERE id=1";

if (mysqli_query($conn, $sql)) {
    echo "Record updated successfully";
} else {
    echo "Error updating record: " . mysqli_error($conn);
}

The above code changes the name field of the record with id 1 in the myTable table to Peter.

Summary

PHP and MYSQL are very important tools in web development. We can use PHP's built-in MYSQL functions to connect, query and modify data in the MYSQL database. In actual development, we need to pay attention to the security and performance of the code, such as using prepared statements to prevent SQL injection attacks, using indexes to improve query efficiency, etc.

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