model 层 联查 $con = Yii::$app->db; $re = $con->createCommand("select * from ads LEFT JOIN nav on nav.id=ads.nav_id")->queryAll(); return $re; model层 修改 $con = Yii::$app->db;return $con->createCommand("update phone set &quo…
(一).集合运算(交.并.补) --(1)Union 并运算 select Sname from Student UNION select Tname From Teacher --(2)INTERSECT 交运算 --查询学校中与老师重名的学生姓名 select Sname From Student INTERSECT --不会重复出现 Select Tname From Teacher --另解 select Sname From Student Where Sname IN (Select…