sql - 如果 stmt 使用 NoRows 或 Int？sql

Question

我对解决这个问题的最佳方法一无所知。当前查询很好。问题是如果没有返回行，我希望 if 语句为真。我也不想写两次查询，所以我如何以 if 语句为真并运行的方式编写它？

IF (select AnInt from ATable where Cond) = expectedInt
begin ... end

Answer 1

如果 aNULL AnInt不可能，那么您可以使不匹配时的空子选择结果等于expectedInt

IF isnull((select AnInt from ATable where Cond), expectedInt) = expectedInt

Answer 2

像这样？

DECLARE @Test INT

SELECT @Test = AnInt
FROM ATable
WHERE Cond

IF @Test IS NULL OR @Test = expectedInt
BEGIN
...
END

Answer 3

IF Coalesce((select TOP 1 AnInt from ATable where Cond),expectedInt) = expectedInt
begin
end