50个常用SQL语句 Student(S#,Sname,Sage,Ssex) 学生表 S#学号，主键 Course(C#,Cname,T#) 课程表 C#课程号，主键 SC(S#,C#,score) 成绩表 Teacher(T#,Tname) 教师表 T#教师编号，主键 问题： 1、查询“001”课程比“002”课程成绩高的所有学生的学号；
select a.S#
from (
select s#,score
from SC
where C#=
'001') a,(
select s#,score
from SC
where C#=
'002') b
where a.score>b.score
and a.s#=b.s#; 2、查询平均成绩大于60分的同学的学号和平均成绩；
select S#,
avg(score)
from sc
group by S#
having avg(score) >60; 3、查询所有同学的学号、姓名、选课数、总成绩；
select Student.S#,Student.Sname,
count(SC.C#),
sum(score)
from Student
left Outer join SC
on Student.S#=SC.S#
group by Student.S#,Sname 4、查询姓“李”的老师的个数；
select count(
distinct(Tname))
from Teacher
where Tname
like '李%'; 5、查询没学过“叶平”老师课的同学的学号、姓名；
select Student.S#,Student.Sname
from Student
where S#
not in (
select distinct( SC.S#)
from SC,Course,Teacher
where SC.C#=Course.C#
and Teacher.T#=Course.T#
and Teacher.Tname=
'叶平'); 6、查询学过“001”并且也学过编号“002”课程的同学的学号、姓名；
select Student.S#,Student.Sname
from Student,SC
where Student.S#=SC.S#
and SC.C#=
'001'and exists(
Select *
from SC
as SC_2
where SC_2.S#=SC.S#
and SC_2.C#=
'002'); 7、查询学过“叶平”老师所教的所有课的同学的学号、姓名；
select S#,Sname
from Student
where S#
in (
select S#
from SC ,Course ,Teacher
where SC.C#=Course.C#
and Teacher.T#=Course.T#
and Teacher.Tname=
'叶平' group by S#
having count(SC.C#)=(
select count(C#)
from Course,Teacher
where Teacher.T#=Course.T#
and Tname=
'叶平')); 8、查询课程编号“002”的成绩比课程编号“001”课程低的所有同学的学号、姓名；
Select S#,Sname
from (
select Student.S#,Student.Sname,score ,(
select score
from SC SC_2
where SC_2.S#=Student.S#
and SC_2.C#=
'002') score2
from Student,SC
where Student.S#=SC.S#
and C#=
'001') S_2
where score2 <score; 9、查询所有课程成绩小于60分的同学的学号、姓名；
select S#,Sname
from Student
where S#
not in (
select Student.S#
from Student,SC
where S.S#=SC.S#
and score>60); 10、查询没有学全所有课的同学的学号、姓名；
select Student.S#,Student.Sname
from Student,SC
where Student.S#=SC.S#
group by Student.S#,Student.Sname
having count(C#) <(
select count(C#)
from Course); 11、查询至少有一门课与学号为“1001”的同学所学相同的同学的学号和姓名；
select S#,Sname
from Student,SC
where Student.S#=SC.S#
and C#
in select C#
from SC
where S#=
'1001'; 12、查询至少学过学号为“001”同学所有一门课的其他同学学号和姓名；
select distinct SC.S#,Sname
from Student,SC
where Student.S#=SC.S#
and C#
in (
select C#
from SC
where S#=
'001'); 13、把“SC”表中“叶平”老师教的课的成绩都更改为此课程的平均成绩；
update SC
set score=(
select avg(SC_2.score)
from SC SC_2
where SC_2.C#=SC.C# )
from Course,Teacher
where Course.C#=SC.C#
and Course.T#=Teacher.T#
and Teacher.Tname=
'叶平'); 14、查询和“1002”号的同学学习的课程完全相同的其他同学学号和姓名；
select S#
from SC
where C#
in (
select C#
from SC
where S#=
'1002')
group by S#
having count(*)=(
select count(*)
from SC
where S#=
'1002'); 15、删除学习“叶平”老师课的SC表记录； Delect SC
from course ,Teacher
where Course.C#=SC.C#
and Course.T#= Teacher.T#
and Tname=
'叶平'; 16、向SC表中插入一些记录，这些记录要求符合以下条件：没有上过编号“003”课程的同学学号、2、 号课的平均成绩；
Insert SC
select S#,
'002',(
Select avg(score)
from SC
where C#=
'002')
from Student
where S#
not in (
Select S#
from SC
where C#=
'002'); 17、按平均成绩从高到低显示所有学生的“数据库”、“企业管理”、“英语”三门的课程成绩，按如下形式显示： 学生ID,,数据库,企业管理,英语,有效课程数,有效平均分
SELECT S#
as 学生ID ,(
SELECT score
FROM SC
WHERE SC.S#=t.S#
AND C#=
'004')
AS 数据库 ,(
SELECT score
FROM SC
WHERE SC.S#=t.S#
AND C#=
'001')
AS 企业管理 ,(
SELECT score
FROM SC
WHERE SC.S#=t.S#
AND C#=
'006')
AS 英语 ,
COUNT(*)
AS 有效课程数,
AVG(t.score)
AS 平均成绩
FROM SC
AS t
GROUP BY S#
ORDER BY avg(t.score) 18、查询各科成绩最高和最低的分：以如下形式显示：课程ID，最高分，最低分
SELECT L.C#
As 课程ID,L.score
AS 最高分,R.score
AS 最低分
FROM SC L ,SC
AS R
WHERE L.C# = R.C#
and L.score = (
SELECT MAX(IL.score)
FROM SC
AS IL,Student
AS IM
WHERE L.C# = IL.C#
and IM.S#=IL.S#
GROUP BY IL.C#)
AND R.Score = (
SELECT MIN(IR.score)
FROM SC
AS IR
WHERE R.C# = IR.C#
GROUP BY IR.C# ); 19、按各科平均成绩从低到高和及格率的百分数从高到低顺序
SELECT t.C#
AS 课程号,
max(course.Cname)
AS 课程名,
isnull(
AVG(score),0)
AS 平均成绩 ,100 *
SUM(
CASE WHEN isnull(score,0)>=60
THEN 1
ELSE 0
END)/
COUNT(*)
AS 及格百分数
FROM SC T,Course
where t.C#=course.C#
GROUP BY t.C#
ORDER BY 100 *
SUM(
CASE WHEN isnull(score,0)>=60
THEN 1
ELSE 0
END)/
COUNT(*)
DESC 20、查询如下课程平均成绩和及格率的百分数(用
"1行"显示): 企业管理（001），马哲（002），OO&UML （003），数据库（004）
SELECT SUM(
CASE WHEN C# =
'001' THEN score
ELSE 0
END)/
SUM(
CASE C#
WHEN '001' THEN 1
ELSE 0
END)
AS 企业管理平均分 ,100 *
SUM(
CASE WHEN C# =
'001' AND score >= 60
THEN 1
ELSE 0
END)/
SUM(
CASE WHEN C# =
'001' THEN 1
ELSE 0
END)
AS 企业管理及格百分数 ,
SUM(
CASE WHEN C# =
'002' THEN score
ELSE 0
END)/
SUM(
CASE C#
WHEN '002' THEN 1
ELSE 0
END)
AS 马哲平均分 ,100 *
SUM(
CASE WHEN C# =
'002' AND score >= 60
THEN 1
ELSE 0
END)/
SUM(
CASE WHEN C# =
'002' THEN 1
ELSE 0
END)
AS 马哲及格百分数 ,
SUM(
CASE WHEN C# =
'003' THEN score
ELSE 0
END)/
SUM(
CASE C#
WHEN '003' THEN 1
ELSE 0
END)
AS UML平均分 ,100 *
SUM(
CASE WHEN C# =
'003' AND score >= 60
THEN 1
ELSE 0
END)/
SUM(
CASE WHEN C# =
'003' THEN 1
ELSE 0
END)
AS UML及格百分数 ,
SUM(
CASE WHEN C# =
'004' THEN score
ELSE 0
END)/
SUM(
CASE C#
WHEN '004' THEN 1
ELSE 0
END)
AS 数据库平均分 ,100 *
SUM(
CASE WHEN C# =
'004' AND score >= 60
THEN 1
ELSE 0
END)/
SUM(
CASE WHEN C# =
'004' THEN 1
ELSE 0
END)
AS 数据库及格百分数
FROM SC 21、查询不同老师所教不同课程平均分从高到低显示
SELECT max(Z.T#)
AS 教师ID,
MAX(Z.Tname)
AS 教师姓名,C.C#
AS 课程ＩＤ,
MAX(C.Cname)
AS 课程名称,
AVG(Score)
AS 平均成绩
FROM SC
AS T,Course
AS C ,Teacher
AS Z
where T.C#=C.C#
and C.T#=Z.T#
GROUP BY C.C#
ORDER BY AVG(Score)
DESC 22、查询如下课程成绩第 3 名到第 6 名的学生成绩单：企业管理（001），马哲（002），UML （003），数据库（004） [学生ID],[学生姓名],企业管理,马哲,UML,数据库,平均成绩
SELECT DISTINCT top 3 SC.S#
As 学生学号, Student.Sname
AS 学生姓名 , T1.score
AS 企业管理, T2.score
AS 马哲, T3.score
AS UML, T4.score
AS 数据库,
ISNULL(T1.score,0) +
ISNULL(T2.score,0) +
ISNULL(T3.score,0) +
ISNULL(T4.score,0)
as 总分
FROM Student,SC
LEFT JOIN SC
AS T1
ON SC.S# = T1.S#
AND T1.C# =
'001' LEFT JOIN SC
AS T2
ON SC.S# = T2.S#
AND T2.C# =
'002' LEFT JOIN SC
AS T3
ON SC.S# = T3.S#
AND T3.C# =
'003' LEFT JOIN SC
AS T4
ON SC.S# = T4.S#
AND T4.C# =
'004' WHERE student.S#=SC.S#
and ISNULL(T1.score,0) +
ISNULL(T2.score,0) +
ISNULL(T3.score,0) +
ISNULL(T4.score,0)
NOT IN (
SELECT DISTINCT TOP 15
WITH TIES
ISNULL(T1.score,0) +
ISNULL(T2.score,0) +
ISNULL(T3.score,0) +
ISNULL(T4.score,0)
FROM sc
LEFT JOIN sc
AS T1
ON sc.S# = T1.S#
AND T1.C# =
'k1' LEFT JOIN sc
AS T2
ON sc.S# = T2.S#
AND T2.C# =
'k2' LEFT JOIN sc
AS T3
ON sc.S# = T3.S#
AND T3.C# =
'k3' LEFT JOIN sc
AS T4
ON sc.S# = T4.S#
AND T4.C# =
'k4' ORDER BY ISNULL(T1.score,0) +
ISNULL(T2.score,0) +
ISNULL(T3.score,0) +
ISNULL(T4.score,0)
DESC); 23、统计列印各科成绩,各分数段人数:课程ID,课程名称,[100-85],[85-70],[70-60],[ <60]
SELECT SC.C#
as 课程ID, Cname
as 课程名称 ,
SUM(
CASE WHEN score
BETWEEN 85
AND 100
THEN 1
ELSE 0
END)
AS [100 - 85] ,
SUM(
CASE WHEN score
BETWEEN 70
AND 85
THEN 1
ELSE 0
END)
AS [85 - 70] ,
SUM(
CASE WHEN score
BETWEEN 60
AND 70
THEN 1
ELSE 0
END)
AS [70 - 60] ,
SUM(
CASE WHEN score < 60
THEN 1
ELSE 0
END)
AS [60 -]
FROM SC,Course
where SC.C#=Course.C#
GROUP BY SC.C#,Cname; 24、查询学生平均成绩及其名次
SELECT 1+(
SELECT COUNT(
distinct 平均成绩)
FROM (
SELECT S#,
AVG(score)
AS 平均成绩
FROM SC
GROUP BY S# )
AS T1
WHERE 平均成绩 > T2.平均成绩)
as 名次, S#
as 学生学号,平均成绩
FROM (
SELECT S#,
AVG(score) 平均成绩
FROM SC
GROUP BY S# )
AS T2
ORDER BY 平均成绩
desc; 25、查询各科成绩前三名的记录:(不考虑成绩并列情况)
SELECT t1.S#
as 学生ID,t1.C#
as 课程ID,Score
as 分数
FROM SC t1
WHERE score
IN (
SELECT TOP 3 score
FROM SC
WHERE t1.C#= C#
ORDER BY score
DESC )
ORDER BY t1.C#; 26、查询每门课程被选修的学生数
select c#,
count(S#)
from sc
group by C#; 27、查询出只选修了一门课程的全部学生的学号和姓名
select SC.S#,Student.Sname,
count(C#)
AS 选课数
from SC ,Student
where SC.S#=Student.S#
group by SC.S# ,Student.Sname
having count(C#)=1; 28、查询男生、女生人数
Select count(Ssex)
as 男生人数
from Student
group by Ssex
having Ssex=
'男';
Select count(Ssex)
as 女生人数
from Student
group by Ssex
having Ssex=
'女'； 29、查询姓“张”的学生名单
SELECT Sname
FROM Student
WHERE Sname
like '张%'; 30、查询同名同性学生名单，并统计同名人数
select Sname,
count(*)
from Student
group by Sname
having count(*)>1;; 31、1981年出生的学生名单(注：Student表中Sage列的类型是datetime)
select Sname,
CONVERT(
char (11),DATEPART(
year,Sage))
as age
from student
where CONVERT(
char(11),DATEPART(
year,Sage))=
'1981'; 32、查询每门课程的平均成绩，结果按平均成绩升序排列，平均成绩相同时，按课程号降序排列
Select C#,
Avg(score)
from SC
group by C#
order by Avg(score),C#
DESC ; 33、查询平均成绩大于85的所有学生的学号、姓名和平均成绩
select Sname,SC.S# ,
avg(score)
from Student,SC
where Student.S#=SC.S#
group by SC.S#,Sname
having avg(score)>85; 34、查询课程名称为“数据库”，且分数低于60的学生姓名和分数
Select Sname,
isnull(score,0)
from Student,SC,Course
where SC.S#=Student.S#
and SC.C#=Course.C#
and Course.Cname=
'数据库'and score <60; 35、查询所有学生的选课情况；
SELECT SC.S#,SC.C#,Sname,Cname
FROM SC,Student,Course
where SC.S#=Student.S#
and SC.C#=Course.C# ; 36、查询任何一门课程成绩在70分以上的姓名、课程名称和分数；
SELECT distinct student.S#,student.Sname,SC.C#,SC.score
FROM student,Sc
WHERE SC.score>=70
AND SC.S#=student.S#; 37、查询不及格的课程，并按课程号从大到小排列
select c#
from sc
where scor e <60
order by C# ; 38、查询课程编号为003且课程成绩在80分以上的学生的学号和姓名；
select SC.S#,Student.Sname
from SC,Student
where SC.S#=Student.S#
and Score>80
and C#=
'003'; 39、求选了课程的学生人数
select count(*)
from sc; 40、查询选修“叶平”老师所授课程的学生中，成绩最高的学生姓名及其成绩
select Student.Sname,score
from Student,SC,Course C,Teacher
where Student.S#=SC.S#
and SC.C#=C.C#
and C.T#=Teacher.T#
and Teacher.Tname=
'叶平' and SC.score=(
select max(score)
from SC
where C#=C.C# ); 41、查询各个课程及相应的选修人数
select count(*)
from sc
group by C#; 42、查询不同课程成绩相同的学生的学号、课程号、学生成绩
select distinct A.S#,B.score
from SC A ,SC B
where A.Score=B.Score
and A.C# <>B.C# ; 43、查询每门功成绩最好的前两名
SELECT t1.S#
as 学生ID,t1.C#
as 课程ID,Score
as 分数
FROM SC t1
WHERE score
IN (
SELECT TOP 2 score
FROM SC
WHERE t1.C#= C#
ORDER BY score
DESC )
ORDER BY t1.C#; 44、统计每门课程的学生选修人数（超过10人的课程才统计）。要求输出课程号和选修人数，查询结果按人数降序排列，查询结果按人数降序排列，若人数相同，按课程号升序排列
select C#
as 课程号,
count(*)
as 人数
from sc
group by C#
order by count(*)
desc,c# 45、检索至少选修两门课程的学生学号
select S#
from sc
group by s#
having count(*) > = 2 46、查询全部学生都选修的课程的课程号和课程名
select C#,Cname
from Course
where C#
in (
select c#
from sc
group by c#) 47、查询没学过“叶平”老师讲授的任一门课程的学生姓名
select Sname
from Student
where S#
not in (
select S#
from Course,Teacher,SC
where Course.T#=Teacher.T#
and SC.C#=course.C#
and Tname=
'叶平'); 48、查询两门以上不及格课程的同学的学号及其平均成绩
select S#,
avg(
isnull(score,0))
from SC
where S#
in (
select S#
from SC
where score <60
group by S#
having count(*)>2)
group by S#; 49、检索“004”课程分数小于60，按分数降序排列的同学学号
select S#
from SC
where C#=
'004'and score <60
order by score
desc; 50、删除“002”同学的“001”课程的成绩
delete from Sc
where S#=
'001'and C#=
'001';
