sql-server-2008 - 有没有办法让失败的 SELECT 不被扔进 TRY/CATCH？

Question

例如:

CREATE PROCEDURE dbo.MyProc
AS
BEGIN
  SET NOCOUNT ON;
  BEGIN TRY
    ...
    DECLARE @Id INT;

    -- I don't want the following line to throw and abort processing. 
    -- I just want @Id to remain NULL. I can add a nested TRY/CATCH, but is there
    -- a better way?
    SET @Id=(SELECT Id FROM MyTable WHERE ...); 
    ...
  END TRY
  BEGIN CATCH
    ...
  END CATCH;
END;

更新:澄清一下，如果返回多行，我希望@Id 保持为 NULL。

Answer 1

我会做这样的事情来避免多行错误:

SELECT top 1 @Id = Id FROM MyTable WHERE ...

或者这个

SELECT @Id = Id FROM MyTable WHERE ...
if @@rowcount > 1
   set @id = null

当有多行时，最后一段会将@Id 设置为空。