SQL - 其他列中每個副本的更新列

Question

我正在查找SQL查詢以將列更新爲另一列中每個副本的相同Id，然後從另一個表中刪除每個重寫的行。

例如

我：

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 

我還需要記錄覆蓋產品編號值，這樣我可以在另一個表中刪除這些行（ 3423,3532和2789應該在另一個表中刪除）。可能在多個查詢中，如果有必要，那沒關係。

達到此目的的最佳方法是什麼？

Answer 1

這並不難，特別是如果你打破了步驟。 檢查了這一點：

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