sql - IS NULL 与 where 子句中的 = NULL + SQL Server

Question

如何检查值IS NULL [or] = @param(其中@param为null)

例如:

Select column1 from Table1
where column2 IS NULL => works fine

如果我想用@param替换比较值(IS NULL)。怎么才能做到这一点

Select column1 from Table1
where column2 = @param => this works fine until @param got some value in it and if is null never finds a record.

如何实现这一点？

Answer 1

select column1 from Table1
  where (@param is null and column2 is null)
     or (column2 = @param)