根据SQL查询条件获取最后的好值？

Question

我需要见下表与输出的查询低于

我列提到Timestamp, A, B, C, D 而且，样本数据如下

Timestamp  A B C D 
------------------------------ 
20-7-2013:2:15 1 360 1 -5 
20-7-2013:7:15 2 360 E -3 
21-7-2013:9:15 N 360 E -6 
21-7-2013:10:15 N 360 E -8 
22-7-2013:11:15 N 360 E -7 

首先，我需要检查列A最后记录值为(NULL or E or -ve)值，如果这三个值都是yes，那么我需要得到最后一个良好值的日期（在A列的情况下输出应该是“20-7-2013：7：15”）取决于条件（0到360之间，> 0，每列-5到+5）。同样对列A到Z以及最终输出做应该

ColumnName  Time 
------------------------- 
    A  20-7-2013:7:15 

更新：对于A列中的输出应该是：20-7-2013：7：15（因为它立即从最后一个NULL值）;列B可以被忽略，因为最后的值是360并且它满足条件;对于C列，输出应该是：20-7-2013：2：15，因为在E错误之前条件是最后的良好值，并且列D输出应该是20-7-2013：7：15，因为它满足条件（-5和+5之间的值）...请帮助

Answer 1

如果不同的列有“好”的值不同的标准，我只想有依次将各列的查询，并UNION在一起

例如

SELECT TOP 1 'A' AS ColumnName, Timestamp AS [Time] FROM <table> 
WHERE A IS NOT NULL AND ISNUMERIC(A) = 1 AND A >= 0 
ORDER BY Timestamp DESC 
UNION 
SELECT TOP 1 'B', Timestamp FROM <table> 
WHERE B IS NOT NULL AND ISNUMERIC(B) = 1 AND B BETWEEN 0 AND 360 
ORDER BY Timestamp DESC 
UNION 
... 

更新： 从下面的评论，我想我明白是怎么回事。 这听起来像每列都有一些条件可以检查，如果最终日期满足条件，也应该排除。我建议围绕列查询的UNION外部查询来移除最后一个值满足的情况。

更新2

SELECT * FROM (
    SELECT TOP 1 'A' AS ColumnName, Timestamp AS [Time] FROM <table> 
    WHERE A IS NOT NULL AND ISNUMERIC(A) = 1 AND A BETWEEN 0 AND 360 
    ORDER BY Timestamp DESC 
    UNION 
    SELECT TOP 1 'B', Timestamp FROM <table> 
    WHERE B IS NOT NULL AND ISNUMERIC(B) = 1 AND B > 0 
    ORDER BY Timestamp DESC 
    UNION 
    SELECT TOP 1 'C', Timestamp FROM <table> 
    WHERE C IS NOT NULL AND ISNUMERIC(C) = 1 AND C BETWEEN -5 AND 5 
    ORDER BY Timestamp DESC 
    UNION 
    SELECT TOP 1 'D', Timestamp FROM <table> 
    WHERE D IS NOT NULL AND ISNUMERIC(D) = 1 AND D BETWEEN -5 AND 5 
    ORDER BY Timestamp DESC 
) Cols 
WHERE [Time] < (SELECT TOP 1 Timestamp FROM <table> ORDER BY Timestamp DESC)