$model=M(''); $model->table(C('DB_PREFIX').'goods as g') ->join(C('DB_PREFIX').'orders as o on o.goods_id=g.id') ->where('o.user_id='.$userid.' and o.state=1 and o.id not in(select c.order_id from '.C('DB_PREFIX').'comment as c where c.user_id='.
一个 SELECT 语句中包含另一个或多个 SELECT 语句就是子查询 WHERE 后: 把 SELECT 查询出来的结果当做条件 # 查询和李四同性别的人 SELECT * FROM students WHERE gender = (SELECT gender FROM students WHERE name = '李四'); FROM 后: 把查询出来的结果当作一个新表(连接查询中的多表) # 把学生表中的男同学查出来 SELECT * FROM (SELECT * FROM studen