Question

我的表格似乎是

Product Id   Status     Line N0     startDate   ENDdate
1            Ordered       3        01/02/1999   NULL
1            Leased        1        02/04/2006   NULL
1            SubLeased     4        12/31/2000   NULL
1            Cancelled     9        10/25/2003   NULL
2            Deliverd      5        01/02/1999   NULL
2            LOST          3        02/04/2001   NULL
2            Cancelled     4        12/31/2000   NULL

我需要在其中写一个更新语句如果状态被取消，则产品结束日期为最大起始日期（亚麻布）

结果应该是

ProductId     EndDate
1             10/25/2003  Date of line number(9)
2             01/02/1999  Date of line number(5)

由于

Answer 1

具有Cancelled行的产品由：

给出

select distinct productid from tbl where status='Cancelled'

这些的最大行号是：

select productid,max(lineno) n from tbl
where productid in (select distinct productid from tbl where status='Cancelled')
group by productid

相应的startdate由：

给出

select a.productid pid,b.n,a.startdate d from tbl a
join (
  select productid,max(lineno) n from tbl
  where productid in (
    select distinct productid from tbl 
    where status='Cancelled'
    )
  group by productid
  )b on (a.productid=b.productid and a.lineno=b.n)

最后，要根据此更新tbl，您应该：

update tbl set enddate=d
from (
  select a.productid pid,b.n,a.startdate d from tbl a
  join (
    select productid,max(lineno) n from tbl
    where productid in (
      select distinct productid from tbl 
      where status='Cancelled'
      )
    group by productid
    )b on (a.productid=b.productid and a.lineno=b.n)
 ) t
where productid=t.pid

如果您只需要更新相关lineno的行，请将and lineno=t.n添加到where子句。

更新语句最多

1 个答案: