ThinkPhp多表查询的有关问题，求帮助

ThinkPhp多表查询的问题，求帮助

PHP code

<!--Code highlighting produced by Actipro CodeHighlighter (freeware)http://www.CodeHighlighter.com/-->public function graduate(){        $this->checkLogin();//判断登录        $Graduate=M('Graduate');        $category=$_GET['category'];        $map['FLG']='0';        $map['LAN']='01';        import("@.ORG.Page");        $count = $Graduate->join('LEFT OUTER JOIN PERSON ON(GRADUATE.PERSONID=PERSON.PERSONID andPERSON.FLG='.$FLG.')')->where($map)->count();        $p = new Page ($count, 10 );        $list=$Graduate->limit($p->firstRow.','.$p->listRows)->join('LEFT OUTER JOIN PERSON ON GRADUATE.PERSONID=PERSON.PERSONID and PERSON.FLG=0')->where($map)->order('GRADUATE.GRADUATEID DESC')->findAll();        $page = $p->show ();        $pagenumber=$p->nowPage;        $this->assign ("pagenumber", $pagenumber-1 );        $this->assign ("page", $page );        $this->assign ("list", $list );        $this->display();    }

Graduate表的personID是Person表的外键，join后查不到值，哪个大侠帮看看什么问题？
还有，这东西分大小写么？
ps：不会php，但是boss让买个bug。。。

------解决方案--------------------
$list=$Graduate->limit($p->firstRow.','.$p->listRows)->join('LEFT OUTER JOIN PERSON ON GRADUATE.PERSONID=PERSON.PERSONID and PERSON.FLG=0')->where($map)->order('GRADUATE.GRADUATEID DESC')->findAll();
后面：
echo $Graduate->getLastSql();
看下最后sql执行语句是什么，是否sql有错误