php连接mysql数据库的4种方法，包括最常用的普通方法、mysqli连接、pdo连接和ADODB连接方式。

1.普通方法（面向过程）

//生成一个连接
$db_connect=mysql_connect($dbhost,$username,$userpass,true) or die(“Unable to connect to the MySQL!”);
//选择一个需要操作的数据库
mysql_select_db($dbdatabase,$db_connect);

2.面向对象mysqli
<?php
$mysqli = new mysqli($dbhost,$username,$userpass,$dbdatabase);
if(mysqli_connect_error()){
echo ‘Could not connect to database.’;
exit;
}
$result=$db->query(“SELECT id,name FROM user”);
$row=$result->fetch_row();

3.pdo连接mysql
$db = new PDO(‘mysql:host=$dbhost;dbname=$dbdatabase’,$username,$userpass);
$db->query(‘select * from user’)->fetch();

4.ADODB连接mysql
require_once ‘./adodb5/adodb.inc.php’;
$conn = &ADONewConnection(‘mysql’);
$conn->connect(‘localhost’,’root’,”,’test’);
$conn->Execute(“set names utf8”);
$res = $conn->Execute(“select * from user”);
if (!$res){
echo $conn->ErrorMsg();
}else{
var_dump($res);
}