查询选修了所有课程的学生
1、首先查询出所有的课程
select kch_id from kcb
2、查询出课程的数目
select count(kch_id) from kcb
3、查询出课程在所有课程中的学生
select xh_id from cjb
where kch_id in (
select kch_id from kcb
)
4、对查询出的课程号进行分组,分组条件为countdistinct kch_id) = (
select count(kch_id) from kcb
)
查询的出的结果即为选修了所有课程的学生
综上所述。即为：
select cjb.xh_id from cjb
where cjb.kch_id in(
select kcb.kch_id from kcb
)
GROUP BY cjb.xh_id
HAVING count(DISTINCT cjb.kch_id) = (
SELECT count(kch_id) from kcb
)
各表分别为：
成绩表cjb(xh_id,kch_id) ---------------->学号,课程号
课程表kcb(kch_id,name)---------------->课程号，课程名
学生表xsb(id,name)---------------------->学号，姓名
------解决方案--------------------
--双重否定的另外一种方法,较我上面给出的好.
- SQL code
--创建测试数据create table Student(S# varchar(10),Sname nvarchar(10),Sage datetime,Ssex nvarchar(10))insert into Student values('01' , N'赵雷' , '1990-01-01' , N'男')insert into Student values('02' , N'钱电' , '1990-12-21' , N'男')insert into Student values('03' , N'孙风' , '1990-05-20' , N'男')insert into Student values('04' , N'李云' , '1990-08-06' , N'男')insert into Student values('05' , N'周梅' , '1991-12-01' , N'女')insert into Student values('06' , N'吴兰' , '1992-03-01' , N'女')insert into Student values('07' , N'郑竹' , '1989-07-01' , N'女')insert into Student values('08' , N'王菊' , '1990-01-20' , N'女')create table Course(C# varchar(10),Cname nvarchar(10),T# varchar(10))insert into Course values('01' , N'语文' , '02')insert into Course values('02' , N'数学' , '01')insert into Course values('03' , N'英语' , '03')create table Teacher(T# varchar(10),Tname nvarchar(10))insert into Teacher values('01' , N'张三')insert into Teacher values('02' , N'李四')insert into Teacher values('03' , N'王五')create table SC(S# varchar(10),C# varchar(10),score decimal(18,1))insert into SC values('01' , '01' , 80)insert into SC values('01' , '02' , 90)insert into SC values('01' , '03' , 99)insert into SC values('02' , '01' , 70)insert into SC values('02' , '02' , 60)insert into SC values('02' , '03' , 80)insert into SC values('03' , '01' , 80)insert into SC values('03' , '02' , 80)insert into SC values('03' , '03' , 80)insert into SC values('04' , '01' , 50)insert into SC values('04' , '02' , 30)insert into SC values('04' , '03' , 20)insert into SC values('05' , '01' , 76)insert into SC values('05' , '02' , 87)insert into SC values('06' , '01' , 31)insert into SC values('06' , '03' , 34)insert into SC values('07' , '02' , 89)insert into SC values('07' , '03' , 98)goselect s.* from student s where not exists(select 1 from course c where not exists(select 1 from sc where sc.c# = c.c# and sc.s# = s.s#))drop table Student,Course,Teacher,SC/*S# Sname Sage Ssex ---------- ---------- ------------------------------------------------------ ---------- 01 赵雷 1990-01-01 00:00:00.000 男02 钱电 1990-12-21 00:00:00.000 男03 孙风 1990-05-20 00:00:00.000 男04 李云 1990-08-06 00:00:00.000 男（所影响的行数为 4 行）*/