SQL檢查空日期和大小寫切換

Question

我有一個數據結果，我想過濾兩個不同的日期。

除了當completion_date爲空時，以下方法正在工作。如果它爲空，我想使用一個名爲created_date的不同字段。

string strSQL = string.Format(@"select * from my_table 

      where user_Id = {0} 

      AND [completion_date] between {1} AND {2} 

      order by completion_status desc, [completion_date] asc" 
      , userId, dateStart, dateEnd, visibilityIndicator); 

也許是這樣的：

string strSQL = string.Format(@"select * from my_table             
where user_Id = {0} 


CASE completion_date 
    WHEN is null THEN [completion_date] between {1} AND {2} 
    ELSE [created_date] between {1} AND {2} 

END 

AND      
      order by completion_status desc, [completion_date] asc" 
      , userId, dateStart, dateEnd, visibilityIndicator); 

什麼是檢查爲空值的最佳方式，然後切換到CREATED_DATE？

Answer 1

where isnull(completetion_date,created_date) between {1} and {2} 

應該工作

Answer 2

string strSQL = string.Format(@"select * from my_table 
where user_Id = {0} 
AND ISNULL([completion_date],[created_date]) between {1} AND {2} 
order by completion_status desc, [completion_date] asc" 

Answer 3

的ANSI SQL兼容的版本：

SELECT * FROM my_table WHERE user_Id = {0} 
AND [completion_date] BETWEEN {1} AND {2} 
OR ([completion_date] IS NULL AND [created_date] BETWEEN {1} AND {2}) 
ORDER BY completion_status DESC, [completion_date] ASC