-----A-------------------------------SELECT 学院.学院名称, count(*) as 各学院人数FROM 班级, 学生, 院系WHERE 班级.院系Id = 院系.院系Id AND 学生.班级Id = 班级.班级IdGROUP BY 学院.学院名称;-----B-------------------------------SELECT 性别, count(*) as 性别对应人数FROM 学生GROUP BY 性别;