关于SQL 语句常用的一些查询收藏

  1 create database xuesheng
  2 go
  3 use xuesheng
  4 go
  5 /*学生表*/
  6 create table Student
  7 (
  8    S# int identity(1,1) primary key,
  9    Sname varchar(50) null,
 10    Sage int not null,
 11    Ssex int not null
 12 )
 13 go
 14 /*教师表*/
 15 create table Teacher
 16 (
 17 T# int identity(1,1) primary key,
 18 Tname varchar(100) null
 19 )
 20 go
 21 /*课程表*/
 22 create table Course
 23 (
 24    C# int identity(1,1) primary key,
 25    Cname varchar(50) null,
 26    T# int foreign key references Teacher(T#)   
 27 )
 28 go
 29 /*成绩表*/
 30 create table SC
 31 (
 32 S# int foreign key references Student(S#),
 33 C# int foreign key references Course(c#), /*课程表*/
 34 score int not null
 35 )
 36 go
 37 
 38 /* 查询平均成绩大于80分的同学的学号和平均成绩 */
 39 select S#,avg(score) from sc group by S# having avg(score) >80
 40 
 41 /*查询所有同学的学号、姓名、选课数、总成绩*/
 42 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
 43 
 44 /*查询姓“李”的老师的个数*/
 45 select count(distinct(Tname)) from Teacher where Tname like '李%'
 46 
 47 /* 5.查询没学过“张老师”老师课的同学的学号、姓名*/ 
 48 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='张老师')
 49 
 50 /*in 的使用方法*/
 51 select * from Student where s# in (1)
 52 /**/
 53 select * from Student where s#=object_id('s#')
 54 /**/
 55 select * from Student where not exists (select * from sc where student.s# =sc.s#)
 56 
 57 /*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*/ 
 58 select C# as 课程号,count(*) as 人数 from sc group by C# order by count(*) desc,c#
 59 
 60 /*检索至少选修两门课程的学生学号*/
 61 select s# from sc group by s# having count(*)>=2
 62 
 63 /*查询各个课程及相应的选修人数 */
 64 select count(*) from sc group by c#
 65 
 66 /*查询每门功成绩最好的前两名*/
 67 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#;
 68 
 69 /************************************************************
 70    统计每门课程的学生选修人数（超过10人的课程才统计）。
 71    要求输出课程号和选修人数，查询结果按人数降序排列，查
 72    询结果按人数降序排列，若人数相同，按课程号升序排列
 73 *************************************************************/
 74 select C# as 课程号,count(*) as 人数 from sc group by C# order by count(*) desc,c#
 75 
 76 
 77 /* 查询全部学生都选修的课程的课程号和课程名 */
 78 select C#,Cname from Course where C# in (select c# from sc group by c#)
 79 
 80 
 81 /* 47、查询没学过“叶平”老师讲授的任一门课程的学生姓名 */
 82 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='张老师')
 83 
 84 
 85 /* 48、查询两门以上不及格课程的同学的学号及其平均成绩 */
 86 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#;
 87 
 88 /* 49、检索“004”课程分数小于60，按分数降序排列的同学学号 */
 89 select S# from SC where C#='1'and score <80 order by score desc;
 90 
 91 
 92 /* 50、删除“002”同学的“001”课程的成绩 */
 93 delete from Sc where S#='001'and C#='001';
 94 
 95 
 96 /* 查询学生平均成绩及其名次 */
 97     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 
 98     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;
 99 
100 
101 /* 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*/ 
102    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 
103    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
104 
105 
106 /* 查询不同老师所教不同课程平均分从高到低显示*/ 
107    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 
108    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
109 
110 
111 /*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,马克思（002），UML （003），数据库（004） [学生ID],[学生姓名],企业管理,马克思,UML,数据库,平均成绩 */
112       SELECT DISTINCT top 3 
113       SC.S# As 学生学号, 
114         Student.Sname AS 学生姓名 , 
115       T1.score AS 企业管理, 
116       T2.score AS 马克思, 
117       T3.score AS UML, 
118       T4.score AS 数据库, 
119       ISNULL(T1.score,0) + ISNULL(T2.score,0) + ISNULL(T3.score,0) + ISNULL(T4.score,0) as 总分 
120       FROM Student,SC LEFT JOIN SC AS T1 
121                       ON SC.S# = T1.S# AND T1.C# = '1' 
122             LEFT JOIN SC AS T2 
123                       ON SC.S# = T2.S# AND T2.C# = '2' 
124             LEFT JOIN SC AS T3 
125                       ON SC.S# = T3.S# AND T3.C# = '3' 
126             LEFT JOIN SC AS T4 
127                       ON SC.S# = T4.S# AND T4.C# = '4' 
128       WHERE student.S#=SC.S# and 
129       ISNULL(T1.score,0) + ISNULL(T2.score,0) + ISNULL(T3.score,0) + ISNULL(T4.score,0) 
130       NOT IN 
131       (SELECT 
132             DISTINCT 
133             TOP 15 WITH TIES 
134             ISNULL(T1.score,0) + ISNULL(T2.score,0) + ISNULL(T3.score,0) + ISNULL(T4.score,0) 
135       FROM sc 
136             LEFT JOIN sc AS T1 
137                       ON sc.S# = T1.S# AND T1.C# = '1' 
138             LEFT JOIN sc AS T2 
139                       ON sc.S# = T2.S# AND T2.C# = '2' 
140             LEFT JOIN sc AS T3 
141                       ON sc.S# = T3.S# AND T3.C# = '3' 
142             LEFT JOIN sc AS T4 
143                       ON sc.S# = T4.S# AND T4.C# = '4' 
144       ORDER BY ISNULL(T1.score,0) + ISNULL(T2.score,0) + ISNULL(T3.score,0) + ISNULL(T4.score,0) DESC);
145 
146 /*、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] */
147     SELECT SC.C# as 课程ID, Cname as 课程名称 
148         ,SUM(CASE WHEN score BETWEEN 85 AND 100 THEN 1 ELSE 0 END) AS [100 - 85] 
149         ,SUM(CASE WHEN score BETWEEN 70 AND 85 THEN 1 ELSE 0 END) AS [85 - 70] 
150         ,SUM(CASE WHEN score BETWEEN 60 AND 70 THEN 1 ELSE 0 END) AS [70 - 60] 
151         ,SUM(CASE WHEN score < 60 THEN 1 ELSE 0 END) AS [60 -] 
152     FROM SC,Course 
153     where SC.C#=Course.C# 
154     GROUP BY SC.C#,Cname;
155 
156 /*查询学生平均成绩及其名次*/
157       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 
158       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 
159       FROM SC GROUP BY S#) AS T2 ORDER BY 平均成绩 desc;
160 
161 /* 26、查询每门课程被选修的学生数*/ 
162     select c#,count(S#) from sc group by C#;
163 
164 /*27、查询出只选修了2门课程的全部学生的学号和姓名 */ 
165    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#)=2;
166 
167 /*28、查询男生、女生人数*/ 
168     Select count(Ssex) as 男生人数 from Student group by Ssex having Ssex=1
169     Select count(Ssex) as 女生人数 from Student group by Ssex having Ssex=0
170 
171 /* 查询姓“张”的学生名单 */
172     SELECT Sname FROM Student WHERE Sname like '张%';
173 
174 /*30、查询同名同性学生名单，并统计同名人数 */
175    select Sname,count(*) from Student group by Sname having count(*)>1;
176 
177 /*31、1981年出生的学生名单(注：Student表中Sage列的类型是datetime) */
178     select Sname, CONVERT(char (11),DATEPART(year,Sage)) as age from student where CONVERT(char(11),DATEPART(year,Sage))='1980';
179 
180 /*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 */
181     Select C#,Avg(score) from SC group by C# order by Avg(score),C# DESC ;
182 
183 /*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 */
184     select Sname,SC.S# ,avg(score) from Student,SC where Student.S#=SC.S# group by SC.S#,Sname having    avg(score)>80;
185 
186 /*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 */
187     Select Sname,isnull(score,0) from Student,SC,Course where SC.S#=Student.S# and SC.C#=Course.C# and Course.Cname='c#' and score <85;
188 
189 /*35、查询所有学生的选课情况；*/ 
190     SELECT SC.S#,SC.C#,Sname,Cname FROM SC,Student,Course where SC.S#=Student.S# and SC.C#=Course.C# 
191 
192 /*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； */
193     SELECT distinct student.S#,student.Sname,SC.C#,SC.score FROM student,Sc WHERE SC.score>=70 AND SC.S#=student.S#;
194 
195 /*37、查询不及格的课程，并按课程号从大到小排列 */
196     select c# from sc where score<60 order by C# ;
197 
198 /*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；*/ 
199     select SC.S#,Student.Sname from SC,Student where SC.S#=Student.S# and Score>80 and C#='3';
200 
201 /*39、求选了课程的学生人数 */
202     select count(*) from sc;
203 
204 /*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*/ 
205     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='张老师' and SC.score=(select max(score)from SC where C#=C.C# );
206 
207 /*41、查询各个课程及相应的选修人数 */
208     select count(*) from sc group by C#;
209 
210 /*42、查询不同课程成绩相同的学生的学号、课程号、学生成绩 */
211     select distinct A.S#,B.score from SC A ,SC B where A.Score=B.Score and A.C# <>B.C# ;
212 
213 alter table [sc] alter column score int not null;
214 alter table [Student] alter column Sage int null; /*修改字段*/
215 alter table [Student] alter column Ssex int null
216 alter table [dbo].[Student] add Sage int null /*添加字段*/
217 alter table [dbo].[Student] add Ssex int null
218 
219 insert into Student values('党清华',20,1)
220 insert into Student values('张三',25,0)
221 insert into Student values('李四',23,1)
222 insert into Student values('王五',28,0)
223 
224 insert into Teacher values('张老师')
225 insert into Teacher values('李老师')
226 insert into Teacher values('王老师')
227 
228 insert into Course values('c++',1)
229 insert into Course values('C#',2)
230 insert into Course values('asp.net',3)
231 
232 insert into SC values(1,1,80)
233 insert into SC values(2,2,85)
234 insert into SC values(3,3,80)
235 
236 select * from Student
237 select * from Teacher
238 select * from Course
239 select * from SC