All PHP database operation functions: best practices for mysqli_query, mysqli_fetch_assoc, mysqli_close and other functions

Catch all PHP database operation functions: best practices for mysqli_query, mysqli_fetch_assoc, mysqli_close and other functions, specific code examples are required

In PHP development, database operations are very important a part of. The mysqli extension is a commonly used database operation extension in PHP. It provides a series of functions to complete database connection, query, result acquisition and other operations. This article will introduce several commonly used mysqli functions and provide best practices and specific code examples.

1. mysqli_connect connects to the database

The mysqli_connect function is used to connect to the MySQL database. The syntax is as follows:

mysqli_connect(host, username, password, dbname);

Among them, host specifies the host address of the database; username and Password is the username and password of the database; dbname is the name of the database to be connected.

Example:

$host = "localhost";
$username = "root";
$password = "123456";
$dbname = "my_database";

$conn = mysqli_connect($host, $username, $password, $dbname);

if (!$conn) {
    die("数据库连接失败：" . mysqli_connect_error());
}

echo "数据库连接成功！";

2. mysqli_query Execute SQL query

The mysqli_query function is used to execute SQL query statements. The syntax is as follows:

mysqli_query(connection, query);

Among them, connection is the database connection object returned by the mysqli_connect function; query is the SQL query statement to be executed.

Example:

$sql = "SELECT * FROM users";

$result = mysqli_query($conn, $sql);

if (mysqli_num_rows($result) > 0) {
    while ($row = mysqli_fetch_assoc($result)) {
        echo "姓名：" . $row["name"] . "，年龄：" . $row["age"] . "<br>";
    }
} else {
    echo "没有查询到结果。";
}

3. mysqli_fetch_assoc Get query results

The mysqli_fetch_assoc function is used to obtain a row of data in the query result set and returns it in the form of an associative array , the syntax is as follows:

mysqli_fetch_assoc(result);

Among them, result is the query result set returned by the mysqli_query function.

Example:

$sql = "SELECT * FROM users";

$result = mysqli_query($conn, $sql);

if (mysqli_num_rows($result) > 0) {
    while ($row = mysqli_fetch_assoc($result)) {
        echo "姓名：" . $row["name"] . "，年龄：" . $row["age"] . "<br>";
    }
} else {
    echo "没有查询到结果。";
}

4. mysqli_close closes the database connection

The mysqli_close function is used to close the database connection and release related resources. The syntax is as follows:

mysqli_close(connection);

Among them, connection is the database connection object returned by the mysqli_connect function.

Example:

mysqli_close($conn);

echo "数据库连接已关闭。";

To sum up, this article introduces the best practices and specific code examples of commonly used mysqli functions such as mysqli_query, mysqli_fetch_assoc and mysqli_close. By rationally using these functions, PHP database operations can be performed more efficiently. I hope this article will be helpful to your learning and development.

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