Ajax调用返回json，xml数据类型(0517--pm)

一、返回Json型数据：

//Ajax调用返回JSON
public function JsonQuery($sql,$type=1,$db="mydb")
{
//定义数据源
$dsn = "mysql:dbname={$db};host={$this->host}";
//造pdo对象
$pdo = new PDO($dsn,"{$this->uid}","{$this->password}");

//准备执行SQL语句
$st = $pdo->prepare($sql);

//执行预处理语句
if($st->execute())
{
if($type==1)
{
$attr = $st->fetchAll(PDO::FETCH_ASSOC);
return json_encode($attr);
}
else
{
if($st)
{
return "OK";
}
else
{
return "NO";
}
}

}
else
{
echo "执行失败！";
}
}