数据库---查询所用的关键字汇总

--1、 查询Student表中的所有记录的Sname、Ssex和Class列。
select Sname,Ssex,class from Student
--2、 查询教师所有的单位即不重复的Depart列。
select distinct depart from teacher
--3、 查询Student表的所有记录。
select *from student
--4、 查询Score表中成绩在60到80之间的所有记录。
select *from Score where degree between 60 and 80
--5、 查询Score表中成绩为85，86或88的记录。
select *from Score where degree in (85,86,88)
--6、 查询Student表中“95031”班或性别为“女”的同学记录。
select *from student where class='95031' or ssex='女'
--7、 以Class降序查询Student表的所有记录。
select *From student order by class desc
--8、 以Cno升序、Degree降序查询Score表的所有记录。
select *from score order by Cno,Degree desc
--9、 查询“95031”班的学生人数。--聚合函数：针对数据列，计算求和或者计数等一系列算术性操作
select count(*) from student where class='95031'
--sum(),avg(),max(),min()
select MAX(Degree) as maxfen,MIN(Degree) minfen from Score where Cno='3-105'
--10、 查询Score表中的最高分的学生学号和课程号。（子查询或者排序）
select *from score where Degree = (select MAX(degree) from score)
select top 1 *from Score order by Degree desc
--11、 查询每门课的平均成绩。--当分组和聚合结合的时候,先分组,然后对每一组分别进行聚合
select AVG(degree) as 平均成绩,cno from Score group by cno
--12、查询Score表中至少有5名学生选修的并以3开头的课程的平均分数。
select cno,avg(degree) as degreess from score where Cno like '3%'
 group by cno having COUNT(*)>=5 order by degreess
--13、查询分数大于70，小于90的Sno列。
select sno from Score where degree>70 and degree <90
--14、查询所有学生的Sname、Cno和Degree列。
select *from student
select *from score
--逗号隔开查两个表,形成笛卡尔积,然后进行where筛选，通过两个表主外键关系筛选
select sname,cno,degree from student,score where student.Sno=Score.Sno
--
select sname,cno,DEGREE from score
inner join student on Score.Sno=student.Sno
left
right
select student.Sno,sname,ssex,student.Class,Score.Sno,Score.Cno,Score.Degree from student
 left join Score on Student.Sno=Score.sno

15、查询所有学生的Sno、Cname和Degree列。
select *from Score
select *from course
select sno,cname ,degree from score join course on score.cno=course.cno

select sno,(select cname from course where score.cno=course.cno) as 课程名,DEGREE from score

16、查询所有学生的Sname、Cname和Degree列
select sname,cname,DEGREE from Score
join student on Student.Sno=Score.Sno
join Course on Course.Cno=Score.Cno



--17、 查询“95033”班学生的平均分。
select *from score
select avg(DEGREE) from Score where Sno in(select sno from Student where class='95033'
)

18、 假设使用如下命令建立了一个grade表：
create table grade(low  int,upp  int,rank  char(1))
insert into grade values(90,100,’A’)
insert into grade values(80,89,’B’)
insert into grade values(70,79,’C’)
insert into grade values(60,69,’D’)
insert into grade values(0,59,’E’)
现查询所有同学的Sno、Cno和rank列。
select sno,cno,rank from Score join grade on Degree between low and upp order by rank

select sno,cno, (select RANK from grade where score.degree between low and upp) as 级别 from score
 

--19、  查询选修“3-105”课程的成绩高于“109”号同学成绩的所有同学的记录。
select *from Score where Cno='3-105' and Degree >
(select Degree from Score where Cno='3-105' and Sno='107')

--20、查询score中选学多门课程的同学中分数为非最高分成绩的记录。
1.查询学号出现两次及以上的学号出来
select sno from Score group by Sno having COUNT(*)>=2
2.查询步骤1中的学号的人的分数
select *from Score where Sno in (select sno from Score group by Sno having COUNT(*)>=2)
3.查询所有人的分数最高分出来
select max(degree) from Score where Sno in (select sno from Score group by Sno having COUNT(*)>=2)
4.从步骤2的结果中剔除最高分即步骤3的
select *from Score where Sno in (
select sno from Score group by Sno having COUNT(*)>=2
)
 and Degree !=(
 select max(degree) from Score
 )
 
--这个是剔除选多门课的所有人的分数最高分
select *from Score where Sno IN (select Sno from Score GROUP by sno having COUNT(*)>1)
and  Degree not In(
select max(Degree)from Score where Sno IN (select Sno from Score GROUP by sno having COUNT(*)>1)
)

--剔除选多门课的每门课最高分
select *from Score a where Degree not IN
(select MAX(degree) from Score b where b.Cno=a.Cno)
and Sno in (select Sno from Score group by Sno having COUNT(*)>1)

--查询除了每门课最高分学生之外的其他学生分数信息
select *from Score a where Degree not IN
(select MAX(degree) from Score b where b.Cno=a.Cno)


--21、 查询成绩高于学号为“109”、课程号为“3-105”的成绩的所有记录。
select *from Score where Degree > (select Degree from Score where Cno='3-105' and Sno='109')

--22、查询和学号为108的同学同年出生的所有学生的Sno、Sname和Sbirthday列。
select sno, sname, sbirthday from student where YEAR(Sbirthday) =
(select year(Sbirthday) from Student where Sno='109')

--时间日期函数：
    YEAR(时间日期列)   ： 取年份
    month():取月份值
    day():取日期值
    dayofyear
select *from Student where year(Sbirthday) > 1976
select sno,sname,dayofyear(sbirthday) as 年份,sbirthday from student

select dateadd(weekday
,1,'1999-03-22')
print datediff(day,'2016-2-22','2015-4-23')
print datename(weekday,'2015-4-23')
print datepart(weekday,'2015-4-23')

print isdate('1999-2-3')
print sysdatetime()
select  getdate()


--23、查询“张旭“教师任课的学生成绩。
select *from score where Cno in
 (select Cno from Course where Tno in
 (select Tno from Teacher where Tname='张旭'))

--24、查询选修某课程的同学人数多于5人的教师姓名。
select tname from Teacher where Tno in
(select Tno from Course where Cno in
(select Cno from Score group by Cno having COUNT(*)>5))

--25、查询95033班和95031班全体学生的记录。
select *from student where class in ('95033','95031')
select *from Score where Sno in (select sno from student where class in ('95033','95031'))
select * from Student,Score where class in ('95033','95031') and Student.Sno=Score.sno
--26、  查询存在有85分以上成绩的课程Cno.
select distinct cno from Score where Degree>=85

--27、查询出“计算机系“教师所教课程的成绩表。
select *from score where cno in (
select cno from course where tno in (
select tno from teacher where depart='计算机系'))

--28、查询“计算机系”与“电子工程系“不同职称的教师的Tname和Prof。
select tname,prof from teacher where prof not in (
select prof from teacher where depart = '电子工程系' and prof in(select prof from teacher where depart = '计算机系')
) and depart in ('计算机系','电子工程系')

--查询两个系中相同职称的职称名称
select prof from teacher where depart = '电子工程系' and prof in(select prof from teacher where depart = '计算机系')

select tname,prof from Teacher a where Prof not in (select Prof from Teacher b where a.Prof=b.Prof and a.Depart='计算机系' and b.Depart='电子工程系')

--29、查询选修编号为“3-105“课程且成绩至少高于选修编号为“3-245”的同学的Cno、Sno和Degree,并按Degree从高到低次序排序。
select *from score where cno='1-101' and degree>(select MIN(degree) from score where cno='1-102') order by degree desc
select *from score where cno='1-101' and degree >any(select degree from score where cno='1-102')

--30、查询选修编号为“3-105”且成绩高于选修编号为“3-245”课程的同学的Cno、Sno和Degree.
select *from score where cno='1-101' and degree >all(select degree from score where cno='1-102')

--31、 查询所有教师和同学的name、sex和birthday.
select sname,ssex,sbirthday from student
union
select tname,tsex,tbirthday from teacher
--注意:列数要对应,列的类型要按先后顺序对应

--32、查询所有“女”教师和“女”同学的name、sex和birthday.
select sname,ssex,sbirthday from student where ssex='女'
union
select tname,tsex,tbirthday from teacher where tsex='女'

--33、 查询成绩比该课程平均成绩低的同学的成绩表。--相关子查询
select * from score a where a.Degree<
(select AVG(degree) from score b where b.cno=a.Cno)

select avg(degree) from score where cno='2-104'

--34、 查询所有任课教师的Tname和Depart.
select tname,depart from teacher where tno in (select distinct tno from course)

--35 、 查询所有未讲课的教师的Tname和Depart.
select tname,depart from teacher where tno not in (select distinct tno from course)

--36、查询至少有2名男生的班号。
select class From student where ssex='男' group by class having COUNT(*)>=2

--37、查询Student表中不姓“王”的同学记录。
select *from student where sname not like '王%'

--38、查询Student表中每个学生的姓名和年龄。
select sname,YEAR(GETDATE())-year(sbirthday) as 年龄 from student

--39、查询Student表中最大和最小的Sbirthday日期值。
select MAX(sbirthday) ,MIN(sbirthday) from student

--40、以班号和年龄从大到小的顺序查询Student表中的全部记录。
select *from student order by class desc,sbirthday asc
--41、查询“男”教师及其所上的课程。
select *from course join teacher on course.tno=teacher.tno where tsex='男'

--42、查询最高分同学的Sno、Cno和Degree列。
select *from score where degree = (select MAX(degree) from score)

--43、查询和“李军”同性别的所有同学的Sname.
select sname from student where ssex in (select ssex from student
where sname='李军')

--44、查询和“李军”同性别并同班的同学Sname.
select sname from student where ssex in (select ssex from student
where sname='李军') and class in (select class from student
where sname='李军')
--45、查询所有选修“计算机导论”课程的“男”同学的成绩表。
select *from score where sno in (select sno from student where ssex = '男') and
cno in (select cno from course where cname='计算机基础')


select *From student
select *From teacher
select *From score
select *From course
update teacher set depart='计算机系' where tno='888'

--处理字符串，以及类型转换

--字符串函数
select LEFT('abcdef',2)--从左往右截取固定长度
select RIGHT('abcdef',2)--从右往左截取
select LOWER('Abc')--转换为小写
select UPPER('acc')--转换为大写
select LEN('qweqwe')--字符串长度int
print LTRIM('    asd  daa                    ')--去除左空格
print LTRIM('    asd  daa')
print rTRIM('    asd  daa                    ')--去除右边空格
print LTRIM('    asd  daa                    ')
print substring('abccccddd',1,2)--从起始位置开始截取固定长度,索引从1开始
print replace('asdaddsdadfasf','as','12312')--替换
print replicate('asd',10)
print str(123.456,5,2)
print space(100)
print 'aasdfas'+'adfdsaf'
print  reverse('abcde')
print patindex('%abc%','123abc123')
print stuff('abcdefghijklmnopqrst',4,0,'zzzz')
--类型转换函数
print cast('123' as int)+12--类型转换
print cast(123 as varchar(20))+'123'
print convert(int,'123')+13
--数学函数
print abs(-13)--绝对值
print ceiling(1.23)--天花板，取上限
print floor(1.9)--地板
print pi()
print rand(10)--随机种子
print round(1.234567,2)--四舍五入
print sqrt(4)--根号
print square(4)--平方

select sname ,'出生日期为'+CAST( YEAR(sbirthday) as varchar(20))+'年'+convert(varchar(20),MONTH(sbirthday))+'月'+cast(DAY(sbirthday) as varchar(20))+'日'  as 出生日期 from student