PHP連接MySQL數據庫的幾種方法

原文：https://www.cnblogs.com/mz0104/p/11811883.html

1.最簡單的方式-mysql（面向過程）

<?php

$con = mysql_connect("localhost","root","password");

$select_db = mysql_select_db('test');

if (!$select_db) {

    die("could not connect to the db:\n" .  mysql_error());

}

//查詢代碼

$sql = "select * from db_table";

$res = mysql_query($sql);

if (!$res) {

    die("could get the res:\n" . mysql_error());

}

while ($row = mysql_fetch_assoc($res)) {

    print_r($row);

}

//查詢代碼

//關閉數據庫連接

mysql_close($con);

?>

2.新的方式-mysqli（面向過程）

$mysql_server_name = 'localhost'; //改成自己的mysql數據庫服務器

$mysql_username = 'root'; //改成自己的mysql數據庫用戶名

$mysql_password = 'password'; //改成自己的mysql數據庫密碼

$mysql_database = 'test'; //改成自己的mysql數據庫名

$conn=mysqli_connect($mysql_server_name,$mysql_username,$mysql_password,$mysql_database); //連接數據庫

//連接數據庫錯誤提示

if (mysqli_connect_errno($conn)) { 

    die("連接 MySQL 失敗: " . mysqli_connect_error()); 

}

mysqli_query($conn,"set names utf8"); //數據庫編碼格式

// mysqli_set_charset($conn,"utf8");//設置默認客戶端字符集。

// mysqli_select_db($conn,$mysql_database); //更改連接的默認數據庫

//查詢代碼

$sql = “select * from db_table”;

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

while($row = mysqli_fetch_array($query)){

    echo $row['title'];

}

//查詢代碼

// 釋放結果集+關閉MySQL數據庫連接

mysqli_free_result($result);

mysqli_close($conn);

3、常用方式-mysqli（面向對象）

//連接數據庫方式1

$conn = new mysqli('localhost', 'root', 'password', 'test');

//連接數據庫方式2

// $conn = new mysqli();

// $conn -> connect('localhost', 'root', 'password', 'test');

//check connection (檢查PHP是否連接上MYSQL)

if ($conn -> connect_errno) {

    printf("Connect failed: %s\n", $conn->connect_error);

    exit();

}

//查詢代碼

$sql = “select * from db_table”;

$query = $conn->query($sql);

while($row = $query->fetch_array()){

    echo $row['title'];

}

//查詢代碼

//釋放結果集+關閉MySQL連接

$query1 -> free_result();

$conn -> close();

4、PDO連接MySQL數據庫

<?php

$db = new PDO('mysql:host=localhost;dbname=test', 'root', 'password');

try {

    foreach ($db->query('select * from db_table') as $row){

    print_r($row);

    }

    $db = null; //關閉數據庫

} catch (PDOException $e) {

    echo $e->getMessage();

}

?>

5、ADODB連接MySQL數據庫

<?php

//安裝驅動-引入類即可

require_once './adodb5/adodb.inc.php';

$conn = &ADONewConnection('mysql');

$conn->connect('localhost','root','password','test');

$conn->Execute("set names utf8");

//查詢代碼

$res = $conn->Execute("select * from db_table");

if (!$res){

    echo $conn->ErrorMsg();

}else{

    var_dump($res);

}

?>

//關閉連接

$conn->close();

6、總結-關閉mysql數據庫的連接方法

MySQL - 面向過程

    mysql_close($conn);

MySQLi - 面向過程

    mysqli_close($conn);

MySQLi - 面向對象

    $conn->close();

PDO

    $conn = null;

ADODB

    $conn->close();

或

    $conn->free();