SQL 检查空日期，然后进行大小写切换答案

【问题标题】：SQL Check for Null Date and then Case SwitchSQL 检查空日期，然后进行大小写切换
【发布时间】：2012-02-21 21:56:53
【问题描述】：

我有一个要按两个不同日期过滤的数据结果。

除了completion_date 为空时，以下内容正常工作。如果它为 null，我想使用另一个名为 created_date 的字段。

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);

大概是这样的：

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);

检查该空值然后切换到 created_date 的最佳方法是什么？

【问题讨论】：

标签： sql switch-statement case

【解决方案1】：

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

应该工作

【讨论】：

【解决方案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"

【讨论】：

【解决方案3】：

ANSI SQL 兼容版本：

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

【讨论】：

还有 ANSI COALESCE 但不确定它是否适用于此...也许吧。
谢谢！一个有趣的解决方案。如果可能，我会尽量避免 Coalesce，这只是个人喜好。