PHP连接MySQL数据库三种实现方法

$mysql_conf = array(
  'host'  => '127.0.0.1:3306', 
  'db'   => 'test', 
  'db_user' => 'root', 
  'db_pwd' => 'root', 
  );
$mysql_conn = @mysql_connect($mysql_conf['host'], $mysql_conf['db_user'], $mysql_conf['db_pwd']);
if (!$mysql_conn) {
  die("could not connect to the database:\n" . mysql_error());//诊断连接错误
}
mysql_query("set names 'utf8'");//编码转化
$select_db = mysql_select_db($mysql_conf['db']);
if (!$select_db) {
  die("could not connect to the db:\n" . mysql_error());
}
$sql = "select  from user;";
$res = mysql_query($sql);
if (!$res) {
  die("could get the res:\n" . mysql_error());
}

while ($row = mysql_fetch_assoc($res)) {
  print_r($row);
}

mysql_close($mysql_conn);

<?php
$mysql_conf = array(
  'host'  => '127.0.0.1:3306', 
  'db'   => 'test', 
  'db_user' => 'root', 
  'db_pwd' => 'joshua317', 
  );

$mysqli = @new mysqli($mysql_conf['host'], $mysql_conf['db_user'], $mysql_conf['db_pwd']);
if ($mysqli->connect_errno) {
  die("could not connect to the database:\n" . $mysqli->connect_error);//诊断连接错误
}
$mysqli->query("set names 'utf8';");//编码转化
$select_db = $mysqli->select_db($mysql_conf['db']);
if (!$select_db) {
  die("could not connect to the db:\n" . $mysqli->error);
}$sql = "select uid from user where name = 'joshua';";
$res = $mysqli->query($sql);
if (!$res) {
  die("sql error:\n" . $mysqli->error);
}
 while ($row = $res->fetch_assoc()) {
    var_dump($row);
  }

$res->free();
$mysqli->close();
?>

<?php
$mysql_conf = array(
  'host'  => '127.0.0.1:3306', 
  'db'   => 'test', 
  'db_user' => 'root', 
  'db_pwd' => 'joshua317', 
  );
try {
  $pdo = new PDO("mysql:host=" . $mysql_conf['host'] . ";dbname=" . $mysql_conf['db'], $mysql_conf['db_user'], $mysql_conf['db_pwd']);//创建一个pdo对象
  $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);  // 设置sql语句查询如果出现问题 就会抛出异常
  //set_exception_handler("cus_exception_handler");
} catch (PDOException $e) {
  die("connect error:".$e->getMessage());
}
$pdo->exec("set names 'utf8'");
$sql = "select  from user where name = ?";
$stmt = $pdo->prepare($sql);
$stmt->bindValue(1, 'joshua', PDO::PARAM_STR);
$rs = $stmt->execute();
if ($rs) {
  // PDO::FETCH_ASSOC 关联数组形式
  // PDO::FETCH_NUM 数字索引数组形式
  while ($row = $stmt->fetch(PDO::FETCH_ASSOC)) {
    var_dump($row);
  }
}