PHP如何插入数据库

<?php$ostype=$_POST['ostype']; $uuid=$_POST['uuid'];$nowtime=time();$username='XXXX';$userpass='XXXX';$dbhost='localhost';$dbdatabase='XXX';//生成一个连接$db_connect=mysql_connect($dbhost,$username,$userpass) or die("Unable to connect to the MySQL!");$ret_json;if(!$db_connect) { 	$ret_json=array('code'=>1001, 'message'=>'链接数据库失败');} else {	mysql_select_db($dbdatabase,$db_connect);	$result = mysql_query("INSERT INTO t_dblocal_userinformation (ID, OSTYPE, UUID, LASTDATE) VALUES (NULL, $ostype, $uuid, $nowtime)");	if ($result) {		$ret_json=array('code'=>1000, 'message'=>'插入数据库成功');	}	else {		$ret_json=array('code'=>1002, 'message'=>'插入数据库失败');	}}$jobj=new stdclass();foreach($ret_json as $key=>$value){$jobj->$key=$value;}echo ''.json_encode($jobj);?>

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ''t_dblocal_userinformation'('ID', 'UUID', 'OSTYPE', 'LASTDATE') VALUES (NULL, 'E' at line 1