1 /*
  2 标题：一个项目涉及到的50个Sql语句(整理版)
  3 作者：爱新觉罗.毓华(十八年风雨，守得冰山雪莲花开)
  4 时间：2010-05-10
  5 地点：重庆航天职业学院
  6 说明：以下五十个语句都按照测试数据进行过测试，最好每次只单独运行一个语句。
  7 问题及描述：
  8 --1.学生表
  9 Student(S#,Sname,Sage,Ssex) --S# 学生编号,Sname 学生姓名,Sage 出生年月,Ssex 学生性别
 10 --2.课程表 
 11 Course(C#,Cname,T#) --C# --课程编号,Cname 课程名称,T# 教师编号
 12 --3.教师表 
 13 Teacher(T#,Tname) --T# 教师编号,Tname 教师姓名
 14 --4.成绩表 
 15 SC(S#,C#,score) --S# 学生编号,C# 课程编号,score 分数
 16 */
 17 --创建测试数据
 18 create table Student(S# varchar(10),Sname nvarchar(10),Sage datetime,Ssex nvarchar(10))
 19 insert into Student values(‘01‘ , N‘赵雷‘ , ‘1990-01-01‘ , N‘男‘)
 20 insert into Student values(‘02‘ , N‘钱电‘ , ‘1990-12-21‘ , N‘男‘)
 21 insert into Student values(‘03‘ , N‘孙风‘ , ‘1990-05-20‘ , N‘男‘)
 22 insert into Student values(‘04‘ , N‘李云‘ , ‘1990-08-06‘ , N‘男‘)
 23 insert into Student values(‘05‘ , N‘周梅‘ , ‘1991-12-01‘ , N‘女‘)
 24 insert into Student values(‘06‘ , N‘吴兰‘ , ‘1992-03-01‘ , N‘女‘)
 25 insert into Student values(‘07‘ , N‘郑竹‘ , ‘1989-07-01‘ , N‘女‘)
 26 insert into Student values(‘08‘ , N‘王菊‘ , ‘1990-01-20‘ , N‘女‘)
 27 create table Course(C# varchar(10),Cname nvarchar(10),T# varchar(10))
 28 insert into Course values(‘01‘ , N‘语文‘ , ‘02‘)
 29 insert into Course values(‘02‘ , N‘数学‘ , ‘01‘)
 30 insert into Course values(‘03‘ , N‘英语‘ , ‘03‘)
 31 create table Teacher(T# varchar(10),Tname nvarchar(10))
 32 insert into Teacher values(‘01‘ , N‘张三‘)
 33 insert into Teacher values(‘02‘ , N‘李四‘)
 34 insert into Teacher values(‘03‘ , N‘王五‘)
 35 create table SC(S# varchar(10),C# varchar(10),score decimal(18,1))
 36 insert into SC values(‘01‘ , ‘01‘ , 80)
 37 insert into SC values(‘01‘ , ‘02‘ , 90)
 38 insert into SC values(‘01‘ , ‘03‘ , 99)
 39 insert into SC values(‘02‘ , ‘01‘ , 70)
 40 insert into SC values(‘02‘ , ‘02‘ , 60)
 41 insert into SC values(‘02‘ , ‘03‘ , 80)
 42 insert into SC values(‘03‘ , ‘01‘ , 80)
 43 insert into SC values(‘03‘ , ‘02‘ , 80)
 44 insert into SC values(‘03‘ , ‘03‘ , 80)
 45 insert into SC values(‘04‘ , ‘01‘ , 50)
 46 insert into SC values(‘04‘ , ‘02‘ , 30)
 47 insert into SC values(‘04‘ , ‘03‘ , 20)
 48 insert into SC values(‘05‘ , ‘01‘ , 76)
 49 insert into SC values(‘05‘ , ‘02‘ , 87)
 50 insert into SC values(‘06‘ , ‘01‘ , 31)
 51 insert into SC values(‘06‘ , ‘03‘ , 34)
 52 insert into SC values(‘07‘ , ‘02‘ , 89)
 53 insert into SC values(‘07‘ , ‘03‘ , 98)
 54 go
 55 
 56 --1、查询"01"课程比"02"课程成绩高的学生的信息及课程分数
 57 --1.1、查询同时存在"01"课程和"02"课程的情况
 58 select a.* , b.score [课程‘01‘的分数],c.score [课程‘02‘的分数] from Student a , SC b , SC c 
 59 where a.S# = b.S# and a.S# = c.S# and b.C# = ‘01‘ and c.C# = ‘02‘ and b.score > c.score
 60 --1.2、查询同时存在"01"课程和"02"课程的情况和存在"01"课程但可能不存在"02"课程的情况(不存在时显示为null)(以下存在相同内容时不再解释)
 61 select a.* , b.score [课程"01"的分数],c.score [课程"02"的分数] from Student a 
 62 left join SC b on a.S# = b.S# and b.C# = ‘01‘
 63 left join SC c on a.S# = c.S# and c.C# = ‘02‘
 64 where b.score > isnull(c.score,0)
 65 
 66 --2、查询"01"课程比"02"课程成绩低的学生的信息及课程分数
 67 --2.1、查询同时存在"01"课程和"02"课程的情况
 68 select a.* , b.score [课程‘01‘的分数],c.score [课程‘02‘的分数] from Student a , SC b , SC c 
 69 where a.S# = b.S# and a.S# = c.S# and b.C# = ‘01‘ and c.C# = ‘02‘ and b.score < c.score
 70 --2.2、查询同时存在"01"课程和"02"课程的情况和不存在"01"课程但存在"02"课程的情况
 71 select a.* , b.score [课程"01"的分数],c.score [课程"02"的分数] from Student a 
 72 left join SC b on a.S# = b.S# and b.C# = ‘01‘
 73 left join SC c on a.S# = c.S# and c.C# = ‘02‘
 74 where isnull(b.score,0) < c.score
 75 
 76 --3、查询平均成绩大于等于60分的同学的学生编号和学生姓名和平均成绩
 77 select a.S# , a.Sname , cast(avg(b.score) as decimal(18,2)) avg_score
 78 from Student a , sc b
 79 where a.S# = b.S#
 80 group by a.S# , a.Sname
 81 having cast(avg(b.score) as decimal(18,2)) >= 60 
 82 order by a.S#
 83 
 84 --4、查询平均成绩小于60分的同学的学生编号和学生姓名和平均成绩
 85 --4.1、查询在sc表存在成绩的学生信息的SQL语句。
 86 select a.S# , a.Sname , cast(avg(b.score) as decimal(18,2)) avg_score
 87 from Student a , sc b
 88 where a.S# = b.S#
 89 group by a.S# , a.Sname
 90 having cast(avg(b.score) as decimal(18,2)) < 60 
 91 order by a.S#
 92 --4.2、查询在sc表中不存在成绩的学生信息的SQL语句。
 93 select a.S# , a.Sname , isnull(cast(avg(b.score) as decimal(18,2)),0) avg_score
 94 from Student a left join sc b
 95 on a.S# = b.S#
 96 group by a.S# , a.Sname
 97 having isnull(cast(avg(b.score) as decimal(18,2)),0) < 60 
 98 order by a.S#
 99 
100 --5、查询所有同学的学生编号、学生姓名、选课总数、所有课程的总成绩
101 --5.1、查询所有有成绩的SQL。
102 select a.S# [学生编号], a.Sname [学生姓名], count(b.C#) 选课总数, sum(score) [所有课程的总成绩]
103 from Student a , SC b 
104 where a.S# = b.S# 
105 group by a.S#,a.Sname 
106 order by a.S#
107 --5.2、查询所有(包括有成绩和无成绩)的SQL。
108 select a.S# [学生编号], a.Sname [学生姓名], count(b.C#) 选课总数, sum(score) [所有课程的总成绩]
109 from Student a left join SC b 
110 on a.S# = b.S# 
111 group by a.S#,a.Sname 
112 order by a.S#
113 
114 --6、查询"李"姓老师的数量 
115 --方法1
116 select count(Tname) ["李"姓老师的数量] from Teacher where Tname like N‘李%‘
117 --方法2
118 select count(Tname) ["李"姓老师的数量] from Teacher where left(Tname,1) = N‘李‘
119 /*
120 "李"姓老师的数量   
121 ----------- 
122 1
123 */
124 
125 --7、查询学过"张三"老师授课的同学的信息 
126 select distinct Student.* from Student , SC , Course , Teacher 
127 where Student.S# = SC.S# and SC.C# = Course.C# and Course.T# = Teacher.T# and Teacher.Tname = N‘张三‘
128 order by Student.S#
129 
130 --8、查询没学过"张三"老师授课的同学的信息 
131 select m.* from Student m where S# not in (select distinct SC.S# from SC , Course , Teacher where SC.C# = Course.C# and Course.T# = Teacher.T# and Teacher.Tname = N‘张三‘) order by m.S#
132 
133 --9、查询学过编号为"01"并且也学过编号为"02"的课程的同学的信息
134 --方法1
135 select Student.* from Student , SC where Student.S# = SC.S# and SC.C# = ‘01‘ and exists (Select 1 from SC SC_2 where SC_2.S# = SC.S# and SC_2.C# = ‘02‘) order by Student.S#
136 --方法2
137 select Student.* from Student , SC where Student.S# = SC.S# and SC.C# = ‘02‘ and exists (Select 1 from SC SC_2 where SC_2.S# = SC.S# and SC_2.C# = ‘01‘) order by Student.S#
138 --方法3
139 select m.* from Student m where S# in
140 (
141   select S# from
142   (
143     select distinct S# from SC where C# = ‘01‘
144     union all
145     select distinct S# from SC where C# = ‘02‘
146   ) t group by S# having count(1) = 2 
147 )
148 order by m.S#
149 
150 --10、查询学过编号为"01"但是没有学过编号为"02"的课程的同学的信息
151 --方法1
152 select Student.* from Student , SC where Student.S# = SC.S# and SC.C# = ‘01‘ and not exists (Select 1 from SC SC_2 where SC_2.S# = SC.S# and SC_2.C# = ‘02‘) order by Student.S#
153 --方法2
154 select Student.* from Student , SC where Student.S# = SC.S# and SC.C# = ‘01‘ and Student.S# not in (Select SC_2.S# from SC SC_2 where SC_2.S# = SC.S# and SC_2.C# = ‘02‘) order by Student.S#
155 
156 --11、查询没有学全所有课程的同学的信息 
157 --11.1、
158 select Student.*
159 from Student , SC 
160 where Student.S# = SC.S# 
161 group by Student.S# , Student.Sname , Student.Sage , Student.Ssex having count(C#) < (select count(C#) from Course) 
162 --11.2
163 select Student.*
164 from Student left join SC 
165 on Student.S# = SC.S# 
166 group by Student.S# , Student.Sname , Student.Sage , Student.Ssex having count(C#) < (select count(C#) from Course) 
167 
168 --12、查询至少有一门课与学号为"01"的同学所学相同的同学的信息 
169 select distinct Student.* from Student , SC where Student.S# = SC.S# and SC.C# in (select C# from SC where S# = ‘01‘) and Student.S# <> ‘01‘
170 
171 --13、查询和"01"号的同学学习的课程完全相同的其他同学的信息 
172 select Student.* from Student where S# in
173 (select distinct SC.S# from SC where S# <> ‘01‘ and SC.C# in (select distinct C# from SC where S# = ‘01‘) 
174 group by SC.S# having count(1) = (select count(1) from SC where S#=‘01‘)) 
175 
176 --14、查询没学过"张三"老师讲授的任一门课程的学生姓名 
177 select student.* from student where student.S# not in 
178 (select distinct sc.S# from sc , course , teacher where sc.C# = course.C# and course.T# = teacher.T# and teacher.tname = N‘张三‘)
179 order by student.S#
180 
181 --15、查询两门及其以上不及格课程的同学的学号，姓名及其平均成绩 
182 select student.S# , student.sname , cast(avg(score) as decimal(18,2)) avg_score from student , sc 
183 where student.S# = SC.S# and student.S# in (select S# from SC where score < 60 group by S# having count(1) >= 2)
184 group by student.S# , student.sname
185 
186 --16、检索"01"课程分数小于60，按分数降序排列的学生信息
187 select student.* , sc.C# , sc.score from student , sc 
188 where student.S# = SC.S# and sc.score < 60 and sc.C# = ‘01‘
189 order by sc.score desc  
190 
191 --17、按平均成绩从高到低显示所有学生的所有课程的成绩以及平均成绩
192 --17.1 SQL 2000 静态 
193 select a.S# 学生编号 , a.Sname 学生姓名 ,
194        max(case c.Cname when N‘语文‘ then b.score else null end) [语文],
195        max(case c.Cname when N‘数学‘ then b.score else null end) [数学],
196        max(case c.Cname when N‘英语‘ then b.score else null end) [英语],
197        cast(avg(b.score) as decimal(18,2)) 平均分
198 from Student a 
199 left join SC b on a.S# = b.S#
200 left join Course c on b.C# = c.C#
201 group by a.S# , a.Sname
202 order by 平均分 desc
203 --17.2 SQL 2000 动态 
204 declare @sql nvarchar(4000)
205 set @sql = ‘select a.S# ‘ + N‘学生编号‘ + ‘ , a.Sname ‘ + N‘学生姓名‘
206 select @sql = @sql + ‘,max(case c.Cname when N‘‘‘+Cname+‘‘‘ then b.score else null end) [‘+Cname+‘]‘
207 from (select distinct Cname from Course) as t
208 set @sql = @sql + ‘ , cast(avg(b.score) as decimal(18,2)) ‘ + N‘平均分‘ + ‘ from Student a left join SC b on a.S# = b.S# left join Course c on b.C# = c.C#
209 group by a.S# , a.Sname order by ‘ + N‘平均分‘ + ‘ desc‘
210 exec(@sql)
211 --17.3 有关sql 2005的动静态写法参见我的文章《普通行列转换(version 2.0)》或《普通行列转换(version 3.0)》。
212 --18、查询各科成绩最高分、最低分和平均分：以如下形式显示：课程ID，课程name，最高分，最低分，平均分，及格率，中等率，优良率，优秀率
213 --及格为>=60，中等为：70-80，优良为：80-90，优秀为：>=90
214 --方法1
215 select m.C# [课程编号], m.Cname [课程名称], 
216   max(n.score) [最高分],
217   min(n.score) [最低分],
218   cast(avg(n.score) as decimal(18,2)) [平均分],
219   cast((select count(1) from SC where C# = m.C# and score >= 60)*100.0 / (select count(1) from SC where C# = m.C#) as decimal(18,2)) [及格率(%)],
220   cast((select count(1) from SC where C# = m.C# and score >= 70 and score < 80 )*100.0 / (select count(1) from SC where C# = m.C#) as decimal(18,2)) [中等率(%)],
221   cast((select count(1) from SC where C# = m.C# and score >= 80 and score < 90 )*100.0 / (select count(1) from SC where C# = m.C#) as decimal(18,2)) [优良率(%)],
222   cast((select count(1) from SC where C# = m.C# and score >= 90)*100.0 / (select count(1) from SC where C# = m.C#) as decimal(18,2)) [优秀率(%)]
223 from Course m , SC n
224 where m.C# = n.C#
225 group by m.C# , m.Cname
226 order by m.C#
227 --方法2
228 select m.C# [课程编号], m.Cname [课程名称], 
229   (select max(score) from SC where C# = m.C#) [最高分],
230   (select min(score) from SC where C# = m.C#) [最低分],
231   (select cast(avg(score) as decimal(18,2)) from SC where C# = m.C#) [平均分],
232   cast((select count(1) from SC where C# = m.C# and score >= 60)*100.0 / (select count(1) from SC where C# = m.C#) as decimal(18,2)) [及格率(%)],
233   cast((select count(1) from SC where C# = m.C# and score >= 70 and score < 80 )*100.0 / (select count(1) from SC where C# = m.C#) as decimal(18,2)) [中等率(%)],
234   cast((select count(1) from SC where C# = m.C# and score >= 80 and score < 90 )*100.0 / (select count(1) from SC where C# = m.C#) as decimal(18,2)) [优良率(%)],
235   cast((select count(1) from SC where C# = m.C# and score >= 90)*100.0 / (select count(1) from SC where C# = m.C#) as decimal(18,2)) [优秀率(%)]
236 from Course m 
237 order by m.C#
238 
239 --19、按各科成绩进行排序，并显示排名
240 --19.1 sql 2000用子查询完成
241 --Score重复时保留名次空缺
242 select t.* , px = (select count(1) from SC where C# = t.C# and score > t.score) + 1 from sc t order by t.c# , px 
243 --Score重复时合并名次
244 select t.* , px = (select count(distinct score) from SC where C# = t.C# and score >= t.score) from sc t order by t.c# , px 
245 --19.2 sql 2005用rank,DENSE_RANK完成
246 --Score重复时保留名次空缺(rank完成)
247 select t.* , px = rank() over(partition by c# order by score desc) from sc t order by t.C# , px 
248 --Score重复时合并名次(DENSE_RANK完成)
249 select t.* , px = DENSE_RANK() over(partition by c# order by score desc) from sc t order by t.C# , px 
250 
251 --20、查询学生的总成绩并进行排名
252 --20.1 查询学生的总成绩
253 select m.S# [学生编号] , 
254        m.Sname [学生姓名] ,
255        isnull(sum(score),0) [总成绩]
256 from Student m left join SC n on m.S# = n.S# 
257 group by m.S# , m.Sname
258 order by [总成绩] desc
259 --20.2 查询学生的总成绩并进行排名，sql 2000用子查询完成，分总分重复时保留名次空缺和不保留名次空缺两种。
260 select t1.* , px = (select count(1) from 
261 (
262   select m.S# [学生编号] , 
263          m.Sname [学生姓名] ,
264          isnull(sum(score),0) [总成绩]
265   from Student m left join SC n on m.S# = n.S# 
266   group by m.S# , m.Sname
267 ) t2 where 总成绩 > t1.总成绩) + 1 from 
268 (
269   select m.S# [学生编号] , 
270          m.Sname [学生姓名] ,
271          isnull(sum(score),0) [总成绩]
272   from Student m left join SC n on m.S# = n.S# 
273   group by m.S# , m.Sname
274 ) t1
275 order by px
276 
277 select t1.* , px = (select count(distinct 总成绩) from 
278 (
279   select m.S# [学生编号] , 
280          m.Sname [学生姓名] ,
281          isnull(sum(score),0) [总成绩]
282   from Student m left join SC n on m.S# = n.S# 
283   group by m.S# , m.Sname
284 ) t2 where 总成绩 >= t1.总成绩) from 
285 (
286   select m.S# [学生编号] , 
287          m.Sname [学生姓名] ,
288          isnull(sum(score),0) [总成绩]
289   from Student m left join SC n on m.S# = n.S# 
290   group by m.S# , m.Sname
291 ) t1
292 order by px
293 --20.3 查询学生的总成绩并进行排名，sql 2005用rank,DENSE_RANK完成，分总分重复时保留名次空缺和不保留名次空缺两种。
294 select t.* , px = rank() over(order by [总成绩] desc) from
295 (
296   select m.S# [学生编号] , 
297          m.Sname [学生姓名] ,
298          isnull(sum(score),0) [总成绩]
299   from Student m left join SC n on m.S# = n.S# 
300   group by m.S# , m.Sname
301 ) t
302 order by px
303 
304 select t.* , px = DENSE_RANK() over(order by [总成绩] desc) from
305 (
306   select m.S# [学生编号] , 
307          m.Sname [学生姓名] ,
308          isnull(sum(score),0) [总成绩]
309   from Student m left join SC n on m.S# = n.S# 
310   group by m.S# , m.Sname
311 ) t
312 order by px
313 
314 --21、查询不同老师所教不同课程平均分从高到低显示 
315 select m.T# , m.Tname , cast(avg(o.score) as decimal(18,2)) avg_score
316 from Teacher m , Course n , SC o
317 where m.T# = n.T# and n.C# = o.C#
318 group by m.T# , m.Tname
319 order by avg_score desc
320 
321 --22、查询所有课程的成绩第2名到第3名的学生信息及该课程成绩
322 --22.1 sql 2000用子查询完成
323 --Score重复时保留名次空缺
324 select * from (select t.* , px = (select count(1) from SC where C# = t.C# and score > t.score) + 1 from sc t) m where px between 2 and 3 order by m.c# , m.px 
325 --Score重复时合并名次
326 select * from (select t.* , px = (select count(distinct score) from SC where C# = t.C# and score >= t.score) from sc t) m where px between 2 and 3 order by m.c# , m.px 
327 --22.2 sql 2005用rank,DENSE_RANK完成
328 --Score重复时保留名次空缺(rank完成)
329 select * from (select t.* , px = rank() over(partition by c# order by score desc) from sc t) m where px between 2 and 3 order by m.C# , m.px 
330 --Score重复时合并名次(DENSE_RANK完成)
331 select * from (select t.* , px = DENSE_RANK() over(partition by c# order by score desc) from sc t) m where px between 2 and 3 order by m.C# , m.px 
332 
333 --23、统计各科成绩各分数段人数：课程编号,课程名称,[100-85],[85-70],[70-60],[0-60]及所占百分比 
334 --23.1 统计各科成绩各分数段人数：课程编号,课程名称,[100-85],[85-70],[70-60],[0-60]
335 --横向显示
336 select Course.C# [课程编号] , Cname as [课程名称] ,
337   sum(case when score >= 85 then 1 else 0 end) [85-100],
338   sum(case when score >= 70 and score < 85 then 1 else 0 end) [70-85],
339   sum(case when score >= 60 and score < 70 then 1 else 0 end) [60-70],
340   sum(case when score < 60 then 1 else 0 end) [0-60]
341 from sc , Course 
342 where SC.C# = Course.C# 
343 group by Course.C# , Course.Cname
344 order by Course.C#
345 --纵向显示1(显示存在的分数段)
346 select m.C# [课程编号] , m.Cname [课程名称] , 分数段 = (
347   case when n.score >= 85 then ‘85-100‘
348        when n.score >= 70 and n.score < 85 then ‘70-85‘
349        when n.score >= 60 and n.score < 70 then ‘60-70‘
350        else ‘0-60‘
351   end) , 
352   count(1) 数量 
353 from Course m , sc n
354 where m.C# = n.C# 
355 group by m.C# , m.Cname , (
356   case when n.score >= 85 then ‘85-100‘
357        when n.score >= 70 and n.score < 85 then ‘70-85‘
358        when n.score >= 60 and n.score < 70 then ‘60-70‘
359        else ‘0-60‘
360   end)
361 order by m.C# , m.Cname , 分数段
362 --纵向显示2(显示存在的分数段，不存在的分数段用0显示)
363 select m.C# [课程编号] , m.Cname [课程名称] , 分数段 = (
364   case when n.score >= 85 then ‘85-100‘
365        when n.score >= 70 and n.score < 85 then ‘70-85‘
366        when n.score >= 60 and n.score < 70 then ‘60-70‘
367        else ‘0-60‘
368   end) , 
369   count(1) 数量 
370 from Course m , sc n
371 where m.C# = n.C# 
372 group by all m.C# , m.Cname , (
373   case when n.score >= 85 then ‘85-100‘
374        when n.score >= 70 and n.score < 85 then ‘70-85‘
375        when n.score >= 60 and n.score < 70 then ‘60-70‘
376        else ‘0-60‘
377   end)
378 order by m.C# , m.Cname , 分数段
379 
380 --23.2 统计各科成绩各分数段人数：课程编号,课程名称,[100-85],[85-70],[70-60],[<60]及所占百分比 
381 --横向显示
382 select m.C# 课程编号, m.Cname 课程名称,
383   (select count(1) from SC where C# = m.C# and score < 60) [0-60],
384   cast((select count(1) from SC where C# = m.C# and score < 60)*100.0 / (select count(1) from SC where C# = m.C#) as decimal(18,2)) [百分比(%)],
385   (select count(1) from SC where C# = m.C# and score >= 60 and score < 70) [60-70],
386   cast((select count(1) from SC where C# = m.C# and score >= 60 and score < 70)*100.0 / (select count(1) from SC where C# = m.C#) as decimal(18,2)) [百分比(%)],
387   (select count(1) from SC where C# = m.C# and score >= 70 and score < 85) [70-85],
388   cast((select count(1) from SC where C# = m.C# and score >= 70 and score < 85)*100.0 / (select count(1) from SC where C# = m.C#) as decimal(18,2)) [百分比(%)],
389   (select count(1) from SC where C# = m.C# and score >= 85) [85-100],
390   cast((select count(1) from SC where C# = m.C# and score >= 85)*100.0 / (select count(1) from SC where C# = m.C#) as decimal(18,2)) [百分比(%)]
391 from Course m 
392 order by m.C#
393 --纵向显示1(显示存在的分数段)
394 select m.C# [课程编号] , m.Cname [课程名称] , 分数段 = (
395   case when n.score >= 85 then ‘85-100‘
396        when n.score >= 70 and n.score < 85 then ‘70-85‘
397        when n.score >= 60 and n.score < 70 then ‘60-70‘
398        else ‘0-60‘
399   end) , 
400   count(1) 数量 ,  
401   cast(count(1) * 100.0 / (select count(1) from sc where C# = m.C#) as decimal(18,2)) [百分比(%)]
402 from Course m , sc n
403 where m.C# = n.C# 
404 group by m.C# , m.Cname , (
405   case when n.score >= 85 then ‘85-100‘
406        when n.score >= 70 and n.score < 85 then ‘70-85‘
407        when n.score >= 60 and n.score < 70 then ‘60-70‘
408        else ‘0-60‘
409   end)
410 order by m.C# , m.Cname , 分数段
411 --纵向显示2(显示存在的分数段，不存在的分数段用0显示)
412 select m.C# [课程编号] , m.Cname [课程名称] , 分数段 = (
413   case when n.score >= 85 then ‘85-100‘
414        when n.score >= 70 and n.score < 85 then ‘70-85‘
415        when n.score >= 60 and n.score < 70 then ‘60-70‘
416        else ‘0-60‘
417   end) , 
418   count(1) 数量 ,  
419   cast(count(1) * 100.0 / (select count(1) from sc where C# = m.C#) as decimal(18,2)) [百分比(%)]
420 from Course m , sc n
421 where m.C# = n.C# 
422 group by all m.C# , m.Cname , (
423   case when n.score >= 85 then ‘85-100‘
424        when n.score >= 70 and n.score < 85 then ‘70-85‘
425        when n.score >= 60 and n.score < 70 then ‘60-70‘
426        else ‘0-60‘
427   end)
428 order by m.C# , m.Cname , 分数段
429 
430  --24、查询学生平均成绩及其名次 
431 --24.1 查询学生的平均成绩并进行排名，sql 2000用子查询完成，分平均成绩重复时保留名次空缺和不保留名次空缺两种。
432 select t1.* , px = (select count(1) from 
433 (
434   select m.S# [学生编号] , 
435          m.Sname [学生姓名] ,
436          isnull(cast(avg(score) as decimal(18,2)),0) [平均成绩]
437   from Student m left join SC n on m.S# = n.S# 
438   group by m.S# , m.Sname
439 ) t2 where 平均成绩 > t1.平均成绩) + 1 from 
440 (
441   select m.S# [学生编号] , 
442          m.Sname [学生姓名] ,
443          isnull(cast(avg(score) as decimal(18,2)),0) [平均成绩]
444   from Student m left join SC n on m.S# = n.S# 
445   group by m.S# , m.Sname
446 ) t1
447 order by px
448 
449 select t1.* , px = (select count(distinct 平均成绩) from 
450 (
451   select m.S# [学生编号] , 
452          m.Sname [学生姓名] ,
453          isnull(cast(avg(score) as decimal(18,2)),0) [平均成绩]
454   from Student m left join SC n on m.S# = n.S# 
455   group by m.S# , m.Sname
456 ) t2 where 平均成绩 >= t1.平均成绩) from 
457 (
458   select m.S# [学生编号] , 
459          m.Sname [学生姓名] ,
460          isnull(cast(avg(score) as decimal(18,2)),0) [平均成绩]
461   from Student m left join SC n on m.S# = n.S# 
462   group by m.S# , m.Sname
463 ) t1
464 order by px
465 --24.2 查询学生的平均成绩并进行排名，sql 2005用rank,DENSE_RANK完成，分平均成绩重复时保留名次空缺和不保留名次空缺两种。
466 select t.* , px = rank() over(order by [平均成绩] desc) from
467 (
468   select m.S# [学生编号] , 
469          m.Sname [学生姓名] ,
470          isnull(cast(avg(score) as decimal(18,2)),0) [平均成绩]
471   from Student m left join SC n on m.S# = n.S# 
472   group by m.S# , m.Sname
473 ) t
474 order by px
475 
476 select t.* , px = DENSE_RANK() over(order by [平均成绩] desc) from
477 (
478   select m.S# [学生编号] , 
479          m.Sname [学生姓名] ,
480          isnull(cast(avg(score) as decimal(18,2)),0) [平均成绩]
481   from Student m left join SC n on m.S# = n.S# 
482   group by m.S# , m.Sname
483 ) t
484 order by px
485   
486 --25、查询各科成绩前三名的记录
487 --25.1 分数重复时保留名次空缺
488 select m.* , n.C# , n.score from Student m, SC n where m.S# = n.S# and n.score in 
489 (select top 3 score from sc where C# = n.C# order by score desc) order by n.C# , n.score desc
490 --25.2 分数重复时不保留名次空缺，合并名次
491 --sql 2000用子查询实现
492 select * from (select t.* , px = (select count(distinct score) from SC where C# = t.C# and score >= t.score) from sc t) m where px between 1 and 3 order by m.c# , m.px 
493 --sql 2005用DENSE_RANK实现
494 select * from (select t.* , px = DENSE_RANK() over(partition by c# order by score desc) from sc t) m where px between 1 and 3 order by m.C# , m.px 
495 
496 --26、查询每门课程被选修的学生数 
497 select c# , count(S#)[学生数] from sc group by C#
498 
499 --27、查询出只有两门课程的全部学生的学号和姓名 
500 select Student.S# , Student.Sname
501 from Student , SC 
502 where Student.S# = SC.S# 
503 group by Student.S# , Student.Sname
504 having count(SC.C#) = 2
505 order by Student.S#
506  
507 --28、查询男生、女生人数 
508 select count(Ssex) as 男生人数 from Student where Ssex = N‘男‘
509 select count(Ssex) as 女生人数 from Student where Ssex = N‘女‘
510 select sum(case when Ssex = N‘男‘ then 1 else 0 end) [男生人数],sum(case when Ssex = N‘女‘ then 1 else 0 end) [女生人数] from student
511 select case when Ssex = N‘男‘ then N‘男生人数‘ else N‘女生人数‘ end [男女情况] , count(1) [人数] from student group by case when Ssex = N‘男‘ then N‘男生人数‘ else N‘女生人数‘ end
512 
513 --29、查询名字中含有"风"字的学生信息
514 select * from student where sname like N‘%风%‘
515 select * from student where charindex(N‘风‘ , sname) > 0
516 
517 --30、查询同名同性学生名单，并统计同名人数 
518 select Sname [学生姓名], count(*) [人数] from Student group by Sname having count(*) > 1
519  
520 --31、查询1990年出生的学生名单(注：Student表中Sage列的类型是datetime) 
521 select * from Student where year(sage) = 1990
522 select * from Student where datediff(yy,sage,‘1990-01-01‘) = 0
523 select * from Student where datepart(yy,sage) = 1990
524 select * from Student where convert(varchar(4),sage,120) = ‘1990‘
525 
526 --32、查询每门课程的平均成绩，结果按平均成绩降序排列，平均成绩相同时，按课程编号升序排列 
527 select m.C# , m.Cname , cast(avg(n.score) as decimal(18,2)) avg_score
528 from Course m, SC n 
529 where m.C# = n.C#    
530 group by m.C# , m.Cname 
531 order by avg_score desc, m.C# asc
532 
533 --33、查询平均成绩大于等于85的所有学生的学号、姓名和平均成绩 
534 select a.S# , a.Sname , cast(avg(b.score) as decimal(18,2)) avg_score
535 from Student a , sc b
536 where a.S# = b.S#
537 group by a.S# , a.Sname
538 having cast(avg(b.score) as decimal(18,2)) >= 85 
539 order by a.S#
540 
541 --34、查询课程名称为"数学"，且分数低于60的学生姓名和分数 
542 select sname , score
543 from Student , SC , Course 
544 where SC.S# = Student.S# and SC.C# = Course.C# and Course.Cname = N‘数学‘ and score < 60 
545 
546 --35、查询所有学生的课程及分数情况； 
547 select Student.* , Course.Cname , SC.C# , SC.score  
548 from Student, SC , Course 
549 where Student.S# = SC.S# and SC.C# = Course.C# 
550 order by Student.S# , SC.C#
551 
552 --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； 
553 select Student.* , Course.Cname , SC.C# , SC.score  
554 from Student, SC , Course 
555 where Student.S# = SC.S# and SC.C# = Course.C# and SC.score >= 70 
556 order by Student.S# , SC.C# 
557 
558 --37、查询不及格的课程
559 select Student.* , Course.Cname , SC.C# , SC.score  
560 from Student, SC , Course 
561 where Student.S# = SC.S# and SC.C# = Course.C# and SC.score < 60 
562 order by Student.S# , SC.C# 
563 
564 --38、查询课程编号为01且课程成绩在80分以上的学生的学号和姓名； 
565 select Student.* , Course.Cname , SC.C# , SC.score  
566 from Student, SC , Course 
567 where Student.S# = SC.S# and SC.C# = Course.C# and SC.C# = ‘01‘ and SC.score >= 80 
568 order by Student.S# , SC.C# 
569 
570 --39、求每门课程的学生人数 
571 select Course.C# , Course.Cname , count(*) [学生人数]
572 from Course , SC 
573 where Course.C# = SC.C#
574 group by  Course.C# , Course.Cname
575 order by Course.C# , Course.Cname
576 
577 --40、查询选修"张三"老师所授课程的学生中，成绩最高的学生信息及其成绩
578 --40.1 当最高分只有一个时
579 select top 1 Student.* , Course.Cname , SC.C# , SC.score  
580 from Student, SC , Course , Teacher
581 where Student.S# = SC.S# and SC.C# = Course.C# and Course.T# = Teacher.T# and Teacher.Tname = N‘张三‘
582 order by SC.score desc
583 --40.2 当最高分出现多个时
584 select Student.* , Course.Cname , SC.C# , SC.score  
585 from Student, SC , Course , Teacher
586 where Student.S# = SC.S# and SC.C# = Course.C# and Course.T# = Teacher.T# and Teacher.Tname = N‘张三‘ and
587 SC.score = (select max(SC.score) from SC , Course , Teacher where SC.C# = Course.C# and Course.T# = Teacher.T# and Teacher.Tname = N‘张三‘)
588 
589 --41、查询不同课程成绩相同的学生的学生编号、课程编号、学生成绩 
590 --方法1
591 select m.* from SC m ,(select C# , score from SC group by C# , score having count(1) > 1) n 
592 where m.C#= n.C# and m.score = n.score order by m.C# , m.score , m.S#
593 --方法2
594 select m.* from SC m where exists (select 1 from (select C# , score from SC group by C# , score having count(1) > 1) n 
595 where m.C#= n.C# and m.score = n.score) order by m.C# , m.score , m.S#
596 
597 --42、查询每门功成绩最好的前两名 
598 select t.* from sc t where score in (select top 2 score from sc where C# = T.C# order by score desc) order by t.C# , t.score desc
599 
600 --43、统计每门课程的学生选修人数（超过5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，若人数相同，按课程号升序排列  
601 select Course.C# , Course.Cname , count(*) [学生人数]
602 from Course , SC 
603 where Course.C# = SC.C#
604 group by  Course.C# , Course.Cname
605 having count(*) >= 5
606 order by [学生人数] desc , Course.C# 
607 
608 --44、检索至少选修两门课程的学生学号 
609 select student.S# , student.Sname 
610 from student , SC 
611 where student.S# = SC.S# 
612 group by student.S# , student.Sname 
613 having count(1) >= 2
614 order by student.S# 
615 
616 --45、查询选修了全部课程的学生信息 
617 --方法1 根据数量来完成
618 select student.* from student where S# in
619 (select S# from sc group by S# having count(1) = (select count(1) from course))
620 --方法2 使用双重否定来完成
621 select t.* from student t where t.S# not in 
622 (
623   select distinct m.S# from
624   (
625     select S# , C# from student , course 
626   ) m where not exists (select 1 from sc n where n.S# = m.S# and n.C# = m.C#)
627 )
628 --方法3 使用双重否定来完成
629 select t.* from student t where not exists(select 1 from 
630 (
631   select distinct m.S# from
632   (
633     select S# , C# from student , course 
634   ) m where not exists (select 1 from sc n where n.S# = m.S# and n.C# = m.C#)
635 ) k where k.S# = t.S#
636 )
637 
638 --46、查询各学生的年龄
639 --46.1 只按照年份来算
640 select * , datediff(yy , sage , getdate()) [年龄] from student
641 --46.2 按照出生日期来算，当前月日 < 出生年月的月日则，年龄减一
642 select * , case when right(convert(varchar(10),getdate(),120),5) < right(convert(varchar(10),sage,120),5) then datediff(yy , sage , getdate()) - 1 else datediff(yy , sage , getdate()) end [年龄] from student
643 
644 --47、查询本周过生日的学生
645 select * from student where datediff(week,datename(yy,getdate()) + right(convert(varchar(10),sage,120),6),getdate()) = 0
646 
647 --48、查询下周过生日的学生
648 select * from student where datediff(week,datename(yy,getdate()) + right(convert(varchar(10),sage,120),6),getdate()) = -1
649 
650 --49、查询本月过生日的学生
651 select * from student where datediff(mm,datename(yy,getdate()) + right(convert(varchar(10),sage,120),6),getdate()) = 0
652 
653 --50、查询下月过生日的学生
654 select * from student where datediff(mm,datename(yy,getdate()) + right(convert(varchar(10),sage,120),6),getdate()) = -1
655 
656 drop table  Student,Course,Teacher,SC