pdo方式连接数据库

try{ $db = new PDO('mysql:host=127.0.0.1;dbname=test;port=3306;charset=utf8','root','123456');}catch(PDOException $e){ echo 'mysql error: '.$e->getMessage();}

1.excu()方式增删改，不推荐

$sql = "insert into test (username,password) values ('liming',123456)";$res = $db->excu($sql);echo $res //返回受影响的行数 1

2.PDOStatement类，增删改(推荐用这种方式，速度快，可以防止sql注入)
方式1-推荐

$sql = "insert into test (username,password) values (:name,:password)";$data = [':name'=>'liming',':password'=>123456];$stmt = $db->prepare($sql);$res = $stmt->execute($data);echo $res //返回受影响的行数 1

方式2,增删改一样

$name='maoxiaoming';//要插入的数据一定要先用变量定义，不然会报错$password= md5(123456);$sql = $sql = "insert into test (username,password) values (:name,:password)";$stmt = $db->prepare($sql);$stmt->bindParam(':name',$name);$stmt->bindParam(':password',$password);$res = $stmt->execute();echo $res //返回受影响的行数 1

3.PDOStatement类查询所有数据

$sql = "select * from user";$stmt = $db->prepare($sql);$stmt->execute();$res = $stmt->fetchAll(PDO::FATCH_ASSOC);

//查询一条

$sql = "select * from user where id=:id";$data = [':id'=>3];$stmt = $db->prepare($sql);$stmt->execute($data);echo '<pre>';print_r($stmt->fetch(PDO::FETCH_ASSOC));