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  • 按月统计的问题,即数据中没有该月的数据,该月的数据显示为0

    if object_id('pubs..tb') is not null
       drop table tb
    go
    create table tb
    (
    noteid   varchar(10),
    saledate datetime
    )
    insert into tb(noteid,saledate) values('v1','2005-09-12')
    insert into tb(noteid,saledate) values('v2','2005-09-12')
    insert into tb(noteid,saledate) values('v3','2005-09-12')
    insert into tb(noteid,saledate) values('v4','2005-08-12')
    go

    if object_id('pubs..mymonths') is not null
       drop table mymonths
    go
    create table mymonths
    (
    mymonths varchar(7)
    )

    declare @dt1 as datetime
    declare @dt2 as datetime
    set @dt1 = '2005-07-01' --开始时间
    set @dt2 = '2006-10-01' --结束时间
    declare @i as int
    set @i = 1
    declare @cnt as int --月数
    set @cnt = (year(@dt2) - year(@dt1))*12 + (month(@dt2) - month(@dt1) + 1)

    while @i <= @cnt
      begin
        insert into mymonths values(convert(varchar(7),@dt1,120))
        set @dt1 = dateadd(month,1 , @dt1)
        set @i = @i + 1
      end

    select m.mymonths as 月份 , isnull(n.数量,0) as 数量 from mymonths m
    left join
    (select convert(varchar(7),saledate,120) as saledate , count(*) as 数量 from tb group by convert(varchar(7),saledate,120)) n
    on m.mymonths = n.saledate

    drop table tb,mymonths

    月份    数量         
    ------- -----------
    2005-07 0
    2005-08 1
    2005-09 3
    2005-10 0
    2005-11 0
    2005-12 0
    2006-01 0
    2006-02 0
    2006-03 0
    2006-04 0
    2006-05 0
    2006-06 0
    2006-07 0
    2006-08 0
    2006-09 0
    2006-10 0

    (所影响的行数为 16 行)

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  • 原文地址:https://www.cnblogs.com/Fooo/p/593108.html
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