Question

我正在尝试在where子句中执行select，其中case语句的结果是列名。

这是我尝试过的：

declare @lang int -- this is passed to the stored procedure
declare @productname nvarchar(300) -- this is passed to the stored procedure

select productid from products where

    case 
    when @lang = 1 then producten
    when @lang = 2 then productit
    when @lang = 3 then productde
    end product like @productname

所以，对于英语（@lang = 1），我想：

select productid from products where producten like @productname

虽然我遇到了错误但不确定我做错了什么。

Answer 1

你想这样说：

case when @lang = 1 then producten
     when @lang = 2 then productit
     when @lang = 3 then productde
end like @productname

或者，或许更清楚：

when @lang = 1 and producten like @productname or
     @lang = 2 and productit like @productname or
     @lang = 3 and productde like @productname

Answer 2

您可以将查询重写为：

declare @lang int -- this is passed to the stored procedure
declare @productname nvarchar(300) -- this is passed to the stored procedure

select productid from products 
where 1= case when @lang = 1 and @productname like producten then 1
              when @lang = 2 and @productname like productit then 1
              when @lang = 3 and @productname like productde then 1
         end

WHERE子句中的case语句，以列名作为条件

2 个答案: