Question

我正在寻找一个SQL查询，将列更新为另一列中每个副本的相同Id，然后从另一个表中删除每个覆盖的行。

例如

我有：

IndustryId      ProductId       ExternalId
144             3332            13
147             3423            13
148             3532            13
2637            63199           32
121             2789            32

我想：

IndustryId      ProductId       ExternalId
144             3332            13
147             3332            13
148             3332            13
2637            63199           32
121             63199           32

我还需要记录覆盖的ProductId值，以便我可以删除另一个表中的那些行（3423,3532和2789应该在另一个表中删除）。如果需要，可以在多个查询中，这无关紧要。

实现这一目标的最佳方法是什么？

Answer 1

这不是太难，特别是如果你打破了步骤。看看这个：

if object_id('tempdb..#myData') is not null
    drop table #myData;

create table #myData ( industryid int, productId int, externalId int);

insert into #myData (industryId, productId, externalId)
values (144,3332,13);
insert into #myData (industryId, productId, externalId)
values (147,3423,13);
insert into #myData (industryId, productId, externalId)
values (148,3532,13);
insert into #myData (industryId, productId, externalId)
values (2637,63199,32);
insert into #myData (industryId, productId, externalId)
values (121,2789,32);

                        --select * from #myData;
-------------------------------------------------
if object_id('tempdb..#IdsToKeep') is not null
    drop table #IdsToKeep;
if object_id('tempdb..#badRows') is not null
    drop table #badRows;

create table #IdsToKeep (externalId int, productId int);
create table #badRows ( industryId int, productId int, externalId int);

insert into #IdsToKeep 
select
    externalId, min(productId)
from
    #myData
group by
    externalId;


--- Capture rows that will be changed ---
insert into #badRows
select
    md.industryId, md.productId, md.externalId
from
    #myData md
        left join #IdsToKeep itk on 
                            md.externalId = itk.externalId
                            and
                            md.productId = itk.productId
where
    itk.productId IS NULL
;


--- Make the update to the main table ---
update 
    #myData
set
    productId = itk.productId
from
    #myData
        inner join #IdsToKeep itk on #myData.externalId = itk.externalId
;


----------
select * from #mydata;
select * from #badRows;

Answer 2

declare @table table (IndustryId int, ProductId int, ExternalId int) insert into @table values (144,3332,13), (147,3423,13), (148,3532,13), (2637,63199,32), (121,2789,32)

select * from @table

;with cte (productid, externalid) as (select max(productid), ExternalId from @table group by ExternalId) select t.IndustryId, c.productid, c.externalid from cte c right outer join @table t on c.externalid = t.ExternalId

SQL - 更新其他列中每个副本的列

2 个答案: