案件和状态有问题

Question

当我没有右侧时，我在列StatusOfDeduplication上得到NULL而不是5.

此查询有什么问题？

select c.Code AS Code, c.DefaultName AS Name, c.Status AS Status,
 case cp.TargetCodeStatus when Null then 5  else cp.TargetCodeStatus end as StatusOfDeduplication from Cities c LEFT JOIN CityPackages cp ON cp.TargetCode = c.Code

Answer 1

使用等号或CASE WHEN无法比较NULL。使用

ISNULL(cp.TargetCodeStatus, 5) AS StatusOfDeduplication 

代替