Question

我有两张桌子：

City表格 - 列CityID，Name，Period
Assets表格 - 列AssetID，Name

我必须更新Period表格的City列，其中AssetID表的Assets与City.Name=Assets.Name的前1位匹配。 Assets表具有相同的不同资产名称。

示例Assets表：

AssetID  Name
1        Asset1
2        Asset1
3        Asset2
4        Asset2

我该怎么做？我尝试了不同的查询，但我无法得到它。

Answer 1

UPDATE City
SET Period = a.AssetID
FROM (SELECT TOP 1 AssetID, Name FROM Assets ORDER BY AssetID ASC) AS a
WHERE City.Name = a.Name;

Answer 2

这应该有效：

update City
set Period = (
    select top 1 a.AssetID
    from Assets a
    where City.Name = a.Name
    order by a.AssetId asc)

要测试的示例代码：

create table #City (CityId varchar(20), [Name] varchar(20), Period varchar(20))
create table #Assets (AssetId varchar(20), [Name] varchar(20))

insert into #City values (1, 'Asset1', null)
insert into #City values (2, 'Asset2', null)
insert into #City values (3, 'Asset3', null)

insert into #Assets values (1, 'Asset1')
insert into #Assets values (2, 'Asset1')
insert into #Assets values (3, 'Asset1')
insert into #Assets values (4, 'Asset2')
insert into #Assets values (5, 'Asset2')
insert into #Assets values (6, 'Asset3')
insert into #Assets values (7, 'Asset3')

select * from #City
select * from #Assets

update #City
set Period = (
    select top 1 a.AssetID
    from #Assets a
    where #City.Name = a.Name
    order by a.AssetId asc)

select * from #City

drop table #City
drop table #Assets

如何更新来自另一个表的TOP 1的列

2 个答案: