MsSqlServer 语句

--假设 成绩>100 优

--假设成绩>90 良

select * from TblScore

select 英语成绩=

(case  when tEnglish>90  then '良' when tEnglish>100 then'优'    end),数学成绩=(case when tMath>90  then '良' when tMath>100 then'优'  end) from TblScore

--第二个练习  1  2  3

select * from user5

select 等级=(case when [level]=1 then'骨灰' when [level]=2 then'菜鸟' when [level]=3then '大神' end) from user5

--第三个练习

--6000 5500 4500

select * from MyOrders

select 销售员,销售总金额=SUM(销售数量*销售价格),称号=(

case

    when SUM(销售价格*销售数量)>6000

    then '金牌'

    when SUM(销售价格*销售数量)>5500

    then '银牌'

    when SUM(销售价格*销售数量)>4500

    then '铜牌'

    else

    '通牌'

end

) from MyOrders

group by 销售员



--收入 支出

select * from test

select number,收入=(

case

    when amount>0    

    then amount

    when amount<0

    then 0

end

),支出=(case

when amount<0



then ABS(amount)

when amount>0

then 0



end) from test



--查询全部的英语成绩  并英语的成绩>90 --子查询做

select * from ( select tEnglish from TblScore ) as t where t.tEnglish>90

--查询性别是男 年龄在20岁以上的

select * from( select * from TblStudent where tSGender='男') as t where t.tSAge>20



--1.查询出班级中全部24岁的男生(子查询)

select * from ( select * from TblStudent where tSGender='男') as t where tSAge=24

--2.查询出高一三班和高二二班的全部学生(子查询)

select * from TblStudent where tSClassId in(

 select tClassId from TblClass where tClassName='高一一班' or tClassName='高二二班')

 

 --2.查出黑马一期和黑马二期的全部学生

 use MyItcast

 select * from student

  select * from TblClass

 

  select * from student where TClassId in(select TClassId from TblClass where TClassName='黑马一期' or TClassName='黑马二期' )



--3.查询出的总人数,男同学多少人,数学平均成绩(子查询)

select 总人数=(select COUNT(*)from student) ,男同学多少人=(select COUNT(*) from student where TSGender=1),数学平均成绩=(select AVG(TblScore.TSMath) from TblScore)





--9条到16条的数据



select * from student

select top 8 * from student where TSId not in(select  top 8 TSId from student) --

--16  到 26

select top 8 * from student where TSId not in( select top 15 TSId from student)

select * from student



use nononodeleteImportant



select * from TblStudent



--每页三条  查第五页的



select * from (

select * ,编号=ROW_NUMBER() over(order by tSid) from TblStudent  ) as newTbl where newTbl.编号 between (5-1)*3+1 and 5*3




--每页9条数据 查询13页的

select * from (

select 编号=ROW_NUMBER() over(order by tSId),* from TblStudent) as t where t.编号 between (13-1)*9+1 and 13*9





select tMath,名次= ROW_NUMBER() over(order by tMath)  from TblScore

select tMath,名次=RANK() over(order by tMath) from TblScore --rank同样成绩的排名同样

select * from MyOrders

select 商品名称,行号=ROW_NUMBER() over(partition by 商品名称 order by id) from MyOrders --partition by 分区



--销售员的销售总金额

select * from MyOrders

select 销售员,销售总金额=SUM(销售数量*销售价格) from MyOrders

group by 销售员



--2.统计每一个销售员(订单)的销售金额占总销售金额的百分比。

select * ,销售数量*销售价格,

百分比=销售数量*销售价格*1.0/SUM(销售数量*销售价格) over(partition by 销售员 )*100

from MyOrders





--链接查询



--查询这个学生的时候能不能把这个学生所在的班级的名字也显示出来

select TblStudent.tSName,TblStudent.tSAge,TblStudent.tSGender,TblClass.tClassName from TblStudent

inner join TblClass

on TblStudent.tSClassId=TblClass.tClassId



--查询这个学生在哪个班级，他（她）的考试成绩

select  TblStudent.tSName,TblStudent.tSGender,TblClass.tClassName,TblScore.tEnglish,TblScore.tMath from TblStudent

inner join TblClass

on TblStudent.tSClassId=TblClass.tClassId

inner join TblScore

on TblStudent.tSId=TblScore.tSId

--创建视图

create view vw_Stu_Cla_Sco_newView

as

select  TblStudent.tSName,TblStudent.tSGender,TblClass.tClassName,TblScore.tEnglish,TblScore.tMath from TblStudent

inner join TblClass

on TblStudent.tSClassId=TblClass.tClassId

inner join TblScore

on TblStudent.tSId=TblScore.tSId

--

select * from vw_Stu_Cla_Sco_newView --查询视图

drop view vw_Stu_Cla_Sco_newView --删除视图





--查询年龄超过20岁的学生的姓名、年龄及所在班级



select TblStudent.tSName,TblStudent.tSAge,TblClass.tClassName from TblStudent

inner join

TblClass

on

TblStudent.tSClassId=TblClass.tClassId

inner join

TblScore

on

TblStudent.tSId=TblScore.tSId

where TblStudent.tSAge>20



--

--查询全部学生(參加及未參加考试的都算)及成绩

select * from TblStudent

inner join TblScore

on TblStudent.tSClassId=TblScore.tSId --參加考试的学生



select TblStudent.tSName, TblScore.tMath,TblScore.tEnglish from TblStudent

left join TblScore

on TblStudent.tSClassId=TblScore.tSId --參加考试的学生和没參加考试的学生





select TblStudent.tSName, TblScore.tMath,TblScore.tEnglish from TblStudent

left join TblScore

on TblStudent.tSClassId=TblScore.tSId

where TblScore.tSId is null --没參加考试的学生



--查询全部參加考试的,english分数不为null学生姓名、年龄及成绩



select TblStudent.tSName, TblScore.tMath,TblScore.tEnglish from TblStudent

inner join TblScore

on TblStudent.tSClassId=TblScore.tSId

where TblScore.tEnglish is not null  --參加考试的学生,英语成绩不为null



--练习3：查询全部学生(參加和未參加考试)的学生姓名、年龄、成绩，假设没有參加考试显示缺考,假设小于english&math60分显示不及格

use nononodeleteImportant

select TblStudent.tSName,TblStudent.tSAge,英语成绩=(case

when tEnglish is null

then '缺考'

else

    CONVERT(nvarchar,tEnglish)

 end),数学成绩=(case

    when tMath IS null

    then '缺考'

    else

    CONVERT(nvarchar,tMath)

  end ),是否及格=(case when tEnglish>60 and tMath>60 then '及格'

  else '不及格'  

   end) from TblStudent left join

TblScore on TblStudent.tSId=TblScore.tSId





select * from TblArea

select t.AreaId,t.AreaName,t1.AreaName from TblArea as t inner join TblArea as t1 on  t.AreaPId=t1.AreaId



--声明变量

declare @number int ;

set @number=30;

print @number

select @number

if(@number=30)

begin

    print '好帅'

end

else

begin

    select '真心恶心'

end







declare @avg int =0

set @avg=(select AVG(tMath) from TblScore)

if(@avg>60)

begin

    select top 3 * from TblScore order by tMath desc

end

else

begin

    select top 3 * from TblScore order by tMath asc

end