Question

我在创建SQL查询时遇到了一些问题。我有一个包含4列'Enquiry Date' , 'Taken Date' , 'Indication Date' , 'Cancelled Date'的表，该表名为tbl_Sales。

我想要做的是创建一个t-sql，看看4列，而GETDATE()的最近日期是当前状态。

因此，例如，如果该行在每列中都有一个日期，并且填写的最后一个日期是昨天在'Cancelled Date'中说明的话，则该行的状态应显示为canceled。

是否可以这样做？

Answer 1

如果您没有某个状态字段，那么您的设计会有些糟糕。这是强力解决方案：

SELECT  *,
        CASE WHEN [Cancelled Date] IS NOT NULL AND 
                  ([Cancelled Date] > [Indication Date] OR [Indication Date] IS NULL) AND
                  ([Cancelled Date] > [Taken Date] OR [Taken Date] IS NULL) AND
                  ([Cancelled Date] > [Enquiry Date] OR [Enquiry Date] IS NULL) THEN 'Canceled'
             WHEN [Indication Date] IS NOT NULL AND 
                  ([Indication Date] > [Cancelled Date] OR [Cancelled Date] IS NULL) AND
                  ([Indication Date] > [Taken Date] OR [Taken Date] IS NULL) AND
                  ([Indication Date] > [Enquiry Date] OR [Enquiry Date] IS NULL) THEN 'Indication'        
             WHEN [Taken Date] IS NOT NULL AND 
                  ([Taken Date] > [Indication Date] OR [Indication Date] IS NULL) AND
                  ([Taken Date] > [Cancelled Date] OR [Cancelled Date] IS NULL) AND
                  ([Taken Date] > [Enquiry Date] OR [Enquiry Date] IS NULL) THEN 'Taken'        
             WHEN [Enquiry Date] IS NOT NULL AND 
                  ([Enquiry Date] > [Indication Date] OR [Indication Date] IS NULL) AND
                  ([Enquiry Date] > [Taken Date] OR [Taken Date] IS NULL) AND
                  ([Enquiry Date] > [Cancelled Date] OR [Cancelled Date] IS NULL) THEN 'Enquiry'        
        END            
FROM Sales

修改

以下是一些缩短版本：

SELECT * FROM Sales CROSS APPLY ( SELECT TOP 1 st FROM ( VALUES ( [Enquiry Date], 'Enquiry'), ( [Taken Date], 'Taken'), ( [Indication Date], 'Indication'), ( [Cancelled Date], 'Canceled') ) d ( dt, st ) ORDER BY dt DESC ) ca

SQL循环检查

1 个答案: