crud创建，修改，删除，查询

BETWEEN 操作符

操作符 BETWEEN ... AND 会选取介于两个值之间的数据范围。这些值可以是数值、文本或者日期。

SELECT column_name(s)
FROM table_name
WHERE column_name
BETWEEN value1 AND value2

运算符：

字符串是用单引号 数据库中出现比较用的是=，不是双等号 逻辑与 and 逻辑或 or 逻辑非 not

CRUD操作

一 C：create 增加，创建，向数据库里面添加数据。

insert into Fruit values('K009','苹果',3.0,'高青',90,'')        --插入表列

insert into Fruit(Ids,Name,Price,Source,Numbers) values('K010','苹果',3.0,'高青',90)

二.R：retrieve检索，查询，从数据库里面查询数据。

1.查询所有

select * from 表名

2.查指定列

select 列名，列名 from 表名

3.替换列名

select Ids '代号',Name '名称',Price '价格',Source '产地' from Fruit

4.查指定行

select * from Fruit where Ids='K006'

select * from Fruit where Price=2.4 and Source='烟台'--查询价格为2.4并且是烟台为产地的  

select * from Fruit where Price between 2.0 and 4.0--查询2.0到4.0之间的价格

 select * from Fruit where Numbers in (90,80,70)--查询所有90,80,70的记录

select*from fruit order by Numbbers asc   --根据Numbers升序来排列,如果不加asc默认以升序排列

select*from 表名 order by 列名 desc    --根据列名降序来排列

select count(*)from 表名    --统计这个表里面有多少条数据

select AVG(列名)from 表名   --求这一列的平均值

select SUM(列名)from 表名   --求这一列的和

select MAX(列名)from 表名  -- 求这一列的最大值

select MIN(列名)from 表名 --求这一列的最小值

三.U：update修改，从数据库表里面修改数据。

update Fruit set Source='烟台' where Ids='K001'

四.D：delete删除，从数据库中删除数据。

delete from Fruit where Ids='K007'

事务：出现了错误，可以进行回滚

加事务：begin tarn

回滚：rollback

--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。

select COUNT(*) from student where class='95031'

--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 select sno,cno from score where degree =(select MAX(degree) from score )--子查询

select top 1 sno,cno from score order by degree desc -- 排序

--11、 查询每门课的平均成绩。 

select cno,AVG(degree) 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) from score group by cno having COUNT(*)>=5 and cno like '3%'

--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 sname,cno,degree from student,score where student.sno=score.sno select sname,cno,degree from student join score on student.sno=score.sno

--15、查询所有学生的Sno、Cname和Degree列。 

select * from course select * from score select sno,cname,degree from course join score on course.cno=score.cno

--16、查询所有学生的Sname、Cname和Degree列。 

select sname,cname,degree from student join score on student.sno = score.sno join course on course.cno = score.cno

--17、 查询“95033”班学生的平均分。 

select AVG(degree) from score where sno in( select sno from student where class='95033')

select AVG(degree) from score join student on student.sno=score.sno and student.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,grade where degree between low and upp

--19、  查询选修“3-105”课程的并且成绩高于“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 sno='109' and cno='3-105')

--20、查询score中选学多门课程的同学,这些同学中分数为非最高分成绩的记录。

select * from s 1.找同学 select sno from score group by sno having COUNT(*)>1 2.找最高分 select MAX(degree) from score where sno in(select sno from score group by sno having COUNT(*)>1) 3.去掉最高分 select sno from score where degree !=(select MAX(degree) from score where sno in(select sno from score group by sno having COUNT(*)>1)) group by sno having COUNT(*)>1 4.找非最高分学生的信息 select * from score where sno in (select sno from score where degree !=(select MAX(degree) from score where sno in(select sno from score group by sno having COUNT(*)>1)) group by sno having COUNT(*)>1)

--21、 查询成绩高于学号为“109”并且课程号为“3-105”的成绩的所有记录。

select * from score where degree>( select degree from score where sno='109' and cno= '3-105')

--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='108')

--23、查询“张旭“教师任课的学生成绩。 select * from teacher select * from score select * from course

1.求张旭的

Tno select tno from teacher where tname='张旭'

2.根据

Tno求Cno select cno from course where tno=(select tno from teacher where tname='张旭')

3.根据Cno求学生成绩 

select * from score where cno = (select cno from course where tno=(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 * from teacher select * from course select tname from teacher where tno=( select tno from course where cno =( 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='95033' or class='95031'

--26、  查询存在有85分以上成绩的课程Cno. 

select * from score 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 teacher select * from course select * from score 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。

--29、查询选修编号为“3-105“课程且成绩至少高于一个选修编号为“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 degree>Any( select degree from  score where cno='3-245')

--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 degree>All( select degree from  score where cno='3-245')

--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

--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

select * from score s1 where degree<( select AVG(degree) from score s2 group by cno having s1.cno = s2.cno )

--34、 查询所有任课教师的Tname和Depart. 

select * from teacher

select * from course select * from score select tname,depart from teacher where tno in( select tno from course where cno in( select distinct cno from score ))

--35 、 查询所有未讲课的教师的Tname和Depart. 

select tname,depart from teacher where tno =( select tno from course where cno not in( select distinct cno from score ))

--36、查询至少有2名男生的班号。 

select * from student select class from student where ssex='男' group by class having COUNT(*)>1

--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) 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

--41、查询“男”教师及其所上的课程。 

select * from course where tno in( select tno from teacher where tsex='男')

--42、查询最高分同学的Sno、Cno和Degree列。

select * from score select top 1 * from score order by degree desc

--43、查询和“李军”同性别的所有同学的Sname. 

select sname from student where ssex=( select ssex from student where sname='李军') and 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=( select ssex from student where sname='李军') and sname !='李军' and class=( select class from student where sname='李军' ) --相关子查询 

select sname from student s1 where ssex=( select ssex from student s2 where sname='李军' and s1.class= s2.class )

--45、查询所有选修“计算机导论”课程的“男”同学的成绩表。

select * from student select * from score select * from course

1.根据计算机导论找cno select cno from course where cname='计算机导论'

2.根据cno在成绩表找sno select sno from score where cno=( select cno from course where cname='计算机导论' )

3.根据sno去学生表找男的 select sno from student where ssex='男' and sno in( select sno from score where cno=( select cno from course where cname='计算机导论' ))

4.根据找到的sno 去成绩表找成绩

select * from score where sno in( select sno from student where ssex='男' and sno in( select sno from score where cno=( select cno from course where cname='计算机导论' )) ) --连接 

select score.sno,score.cno,degree from score join course on score.cno=course.cno join student on student.sno = score.sno and ssex='男' and course.cname='计算机导论'

--横表变纵表或纵表变横表（课下搜索）