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黑马视频-SQL之case

时间:2021-07-01 10:21:17 帮助过:3人阅读

  • tscoreId,
  • tsid,
  • tenglish,
  • 评级=case
  • when tenglish>=95 then ‘优秀‘
  • when tenglish>=90 then ‘良好‘
  • when tenglish>=80 then ‘中‘
  • when tenglish is null then ‘缺考‘
  • else ‘以后的比尔盖茨‘
  • end
  • from TblScore
  • then 后面的数据后类型必须一致
    1. 是等值判断
    2. select
    3. tscoreId,
    4. tsid,
    5. tenglish,
    6. 评级= 
    7. case tenglish
    8. when 100 then ‘一百分‘
    9. when 90 then ‘九十分‘
    10. end
    11. from TblScore
    相当于switch 
    1. Create table Test1(
    2. A int,
    3. B int
    4. )
    5. insert into Test1(10,20)
    6. insert into Test1(100,21)
    7. select A,B,AOrB=
    8. case
    9. when A>B then A
    10. else B
    11. end
    12. from Test1
    统计每个销售员的总销售金额,列出销售员名称,总销售金额、称号(>6000金牌;>5500银牌;...)select     销售员,    销售总金额=sum(销售数量*销售价格),
        称号=    case
            when sum(销售数量*销售价格)>6000 then ‘金牌销售员‘
            when sum(销售数量*销售价格)>5500 then ‘银牌销售员‘
            when sum(销售数量*销售价格)>4500 then ‘铜牌销售员‘
            else ‘普通销售员‘
        end
    from Ordergroup by 销售员order by 销售总金额 desc

    create table Test1(    number varchar(10),
        amount int
    )insert into Test(number ,amount) values  (‘RK1‘,10)insert into Test(number ,amount) values  (‘RK2‘,20)
    insert into Test(number ,amount) values  (‘RK3‘,-30)
    insert into Test(number ,amount) values  (‘RK4‘,-10)
    正数为收入,负数支出
    单号|收入|支出select     number,
        收入=
        case        when amount>0 then amount             
        end






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