How to use PHP back-end functions to develop and implement database operations?

How to use PHP back-end functions to develop and implement database operations?

With the development of the Internet, the demand for dynamic websites has gradually increased, so it is particularly important to use a database system to store and manage data. As a commonly used server-side scripting language, PHP provides rich functions to implement database operations. This article will introduce how to use PHP back-end functions to develop methods to implement database operations, and provide corresponding code examples.

1. Database connection

Before performing database operations, you first need to establish a connection with the database. PHP provides some built-in functions to implement connection operations, the most commonly used of which is the mysqli_connect() function. The following is a sample code to establish a connection with the database:

$servername = "localhost"; //数据库服务器地址
$username = "root"; //数据库用户名
$password = "123456"; //数据库密码
$dbname = "test"; //数据库名称

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

//检测连接是否成功
if (!$conn) {
    die("连接失败: " . mysqli_connect_error());
}
echo "连接成功";

?>

2. Query the data

Once with After the database connection is successfully established, you can start database operations. One of the common operations is querying data. PHP provides multiple functions to perform query operations, such as mysqli_query(), mysqli_fetch_array(), etc. The following is a simple sample code for querying data:

//查询语句
$sql = "SELECT id, name, age FROM users";

//执行查询操作
$result = mysqli_query($conn, $sql);

//处理查询结果
if (mysqli_num_rows($result) > 0) {
    while ($row = mysqli_fetch_assoc($result)) {
        echo "ID: " . $row["id"]. " - Name: " . $row["name"]. " - Age: " . $row["age"]. "<br>";
    }
} else {
    echo "没有查询到数据";
}

//释放内存
mysqli_free_result($result);

?>

3. Insert data

In addition to querying data , inserting data is another common database operation. Insert operations can be performed using the mysqli_query() function. The following is a sample code for inserting data into the database:

//插入语句
$sql = "INSERT INTO users (name, age, email) VALUES ('John Doe', 25, 'john@example.com')";

//执行插入操作
if (mysqli_query($conn, $sql)) {
    echo "数据插入成功";
} else {
    echo "数据插入失败: " . mysqli_error($conn);
}

?>

4. Update data

Update data is Refers to modifying existing data in the database. You can use the mysqli_query() function to perform update operations. The following is a sample code for updating data:

//更新语句
$sql = "UPDATE users SET age = 30 WHERE name = 'John Doe'";

//执行更新操作
if (mysqli_query($conn, $sql)) {
    echo "数据更新成功";
} else {
    echo "数据更新失败: " . mysqli_error($conn);
}

?>

5. Deleting data

Deleting data means to delete data from Delete existing data from the database. Delete operations can be performed using the mysqli_query() function. The following is a sample code to delete data:

//删除语句
$sql = "DELETE FROM users WHERE age < 18";

//执行删除操作
if (mysqli_query($conn, $sql)) {
    echo "数据删除成功";
} else {
    echo "数据删除失败: " . mysqli_error($conn);
}

?>

6. Close the database connection

Finally, after completion After database operations, the connection to the database should be closed to release resources. The connection can be closed using the mysqli_close() function. The following is a sample code to close the database connection:

//关闭连接
mysqli_close($conn);
echo "连接已关闭";

?>

With the above code sample, we can see how to utilize the PHP backend Functions to develop and implement database operations. Of course, the above are only the basic parts of database operations, and actual applications may involve more complex operations. I hope this article will be helpful to readers when performing database operations.

The above is the detailed content of How to use PHP back-end functions to develop and implement database operations?. For more information, please follow other related articles on the PHP Chinese website!