What is the function method for php to connect to mysql database?

The function that PHP uses to connect to the mysql database is mysqli_connect(). This function can open a new connection to the MySQL server. The syntax format is "mysqli_connect(hostname, username, password, database, [port], [ socket]);".

The operating environment of this tutorial: windows7 system, PHP7.1&&mysql8 version, DELL G3 computer

In PHP, you can use the mysqli_connect extension of mysqli () function to realize the connection to the MySQL database. The function syntax format is as follows:

mysqli_connect(host,username,password,dbname,port,socket);

Parameter	Description
host	Optional. Specify the hostname or IP address.
username	Optional. Specifies the MySQL username.
password	Optional. Specifies the MySQL password.
dbname	Optional. Specifies the database to use by default.
port	Optional. Specifies the port number to attempt to connect to the MySQL server.
socket	Optional. Specifies the socket or named pipe to use.

Return value: Returns an object representing the connection to the MySQL server.

It should also be noted that the mysqli_connect() function is an alias of the mysqli::__construct() function, and all objects using mysqli() can also be used to connect to the database.

Example: The following is a simple code to connect to the database.

1) Process-oriented writing method

<?php
    $host     = &#39;localhost&#39;;
    $username = &#39;root&#39;;
    $password = &#39;root&#39;;
    $dbname   = &#39;test&#39;;
    $port     = &#39;3306&#39;;
    $link     = @mysqli_connect($host,$username,$password,$dbname,$port);   // 连接到数据库
    if($link){
        mysqli_set_charset($link,&#39;UTF-8&#39;);      // 设置数据库字符集
        $sql    = &#39;select * from user&#39;;         // SQL 语句
        $result = mysqli_query($link, $sql);    // 执行 SQL 语句，并返回结果
        $data   = mysqli_fetch_all($result);    // 从结果集中获取所有数据
        mysqli_close($link);
    }else{
        die(&#39;数据库连接失败！&#39;);
    }
    echo &#39;<pre class="brush:php;toolbar:false">&#39;;
    print_r($data);
?>

2) Object-oriented writing method

<?php
    $host     = &#39;localhost&#39;;
    $username = &#39;root&#39;;
    $password = &#39;root&#39;;
    $dbname   = &#39;test&#39;;
    $mysql    = new Mysqli($host, $username, $password, $dbname);
    if($mysql -> connect_errno){
        die(&#39;数据库连接失败：&#39;.$mysql->connect_errno);
    }else{
        $mysql -> set_charset(&#39;UTF-8&#39;); //  设置数据库字符集
        $sql = &#39;select * from user&#39;;         // SQL 语句
        $result = $mysql -> query($sql);
        $data = $result -> fetch_all();
        $mysql -> close();
    }
    echo &#39;<pre class="brush:php;toolbar:false">&#39;;
    print_r($data);
?>

The running results are as follows:

Array
(
    [0] => Array
        (
            [0] => 1
            [1] => 张三
        )
)

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