如何检查值IS NULL [or] = @param（@param为空）
IS NULL [or] = @param
前任：
Select column1 from Table1 where column2 IS NULL => works fine
如果我想将比较值（IS NULL）替换为@param。如何才能做到这一点
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？
select column1 from Table1 where (@param is null and column2 is null) or (column2 = @param)
