--查询每门课程的前2名成绩
CREATE TABLE StudentGrade(
stuId CHAR(4),    --学号
subId INT,        --课程号
grade INT,        --成绩
PRIMARY KEY (stuId,subId)
)
GO
--表中数据如下
INSERT INTO StudentGrade(stuId,subId,grade) VALUES('001',1,97);
INSERT INTO StudentGrade(stuId,subId,grade) VALUES('001',2,50);
INSERT INTO StudentGrade(stuId,subId,grade) VALUES('001',3,70);
INSERT INTO StudentGrade(stuId,subId,grade) VALUES('002',1,92);
INSERT INTO StudentGrade(stuId,subId,grade) VALUES('002',2,80);
INSERT INTO StudentGrade(stuId,subId,grade) VALUES('002',3,30);
INSERT INTO StudentGrade(stuId,subId,grade) VALUES('003',1,93);
INSERT INTO StudentGrade(stuId,subId,grade) VALUES('003',2,95);
INSERT INTO StudentGrade(stuId,subId,grade) VALUES('003',3,85);
INSERT INTO StudentGrade(stuId,subId,grade) VALUES('004',1,73);
INSERT INTO StudentGrade(stuId,subId,grade) VALUES('004',2,78);
INSERT INTO StudentGrade(stuId,subId,grade) VALUES('004',3,87);
GO
/*
--查看数据
select * from StudentGrade

--查询结果

001  3 70
001  1 97
002  2 80
002  1 92
003  1 93
003  2 95
004  2 78
004  3 87

SQL语句：

Select * From StudentGrade A
Where (Select Count(*) From StudentGrade  Where stuid= A.stuid And grade> A.grade) < 2
Order By stuid, grade