您需要为 each 设置一个值WHEN
,并且应该有一个ELSE
:
Select Data_Source, CustomerID,
CASE
WHEN Data_Source = 'Test1' and Len(CustomerName) = 35 THEN 'First Value'
WHEN Data_Source = 'Test2' THEN substring(CustomerName, 1, 35)
ELSE 'Sorry, no match.'
END AS CustomerName
From dbo.xx
仅供参考:Len()
不返回字符串。
编辑:
解决一些评论的 SQL Server 答案可能是:
declare @DataSource as Table ( Id Int Identity, CustomerName VarChar(64) )
declare @VariantDataSource as Table ( Id Int Identity, CostumerName VarChar(64) )
insert into @DataSource ( CustomerName ) values ( 'Alice B.' ), ( 'Bob C.' ), ( 'Charles D.' )
insert into @VariantDataSource ( CostumerName ) values ( 'Blush' ), ( 'Dye' ), ( 'Pancake Base' )
select *,
-- Output the CostumerName padded or trimmed to the same length as CustomerName. NULLs are not handled gracefully.
Substring( CostumerName + Replicate( '.', Len( CustomerName ) ), 1, Len( CustomerName ) ) as Clustermere,
-- Output the CostumerName padded or trimmed to the same length as CustomerName. NULLs in CustomerName are explicitly handled.
case
when CustomerName is NULL then ''
when Len( CustomerName ) > Len( CostumerName ) then Substring( CostumerName, 1, Len( CustomerName ) )
else Substring( CostumerName + Replicate( '.', Len( CustomerName ) ), 1, Len( CustomerName ) )
end as 'Crustymore'
from @DataSource as DS inner join
@VariantDataSource as VDS on VDS.Id = DS.Id