有关SELECT的一个最简单的问题
我想要在 select 的结果为空的时候，就换一个结果返回：


@UserIP int

AS
if ISNULL(SELECT CountryID from Cities_CountriesIP where @UserIP>StartIP AND @UserIP<EndIP)
  BEGIN
  SELECT CountryID from Cities_CountriesIP where @UserIP>StartIP AND @UserIP<EndIP
  END
ELSE
  BEGIN
  SELECT CountryID from Cities_CountriesIP where 100663297>StartIP AND 100663297<EndIP
  END

谁知ISNULL这一句出现错误，请问如何判断SELECT的结果为空的情况？

------解决方案--------------------

SQL code

 
SELECT CountryID from Cities_CountriesIP where @UserIP>StartIP AND @UserIP<EndIP

IF @@ROWCOUNT = 0
BEGIN
   SELECT CountryID from Cities_CountriesIP where 100663297>StartIP AND 100663297<EndIP
END