$stcount = M("Results_all")->alias('a')

->join("s_test_name as b on a.subject = b.sid and a.testsets = b.number",'left')

->where("a.subject = $subject and  b.name = '$testsname' ")->field("count(a.number) as cnum")

->select();

你要保守你心，胜过保守一切。

作者：刘俊涛的博客​​