如何将NULL视为最大日期而不是在MySQL中忽略它? [英] How consider NULL as the MAX date instead of ignoring it in MySQL?

问题描述

让我们说我有一个名为test的表，如下所示:

Lets say that I have a table named test like this:

ID   DATE     

1     '2013-01-26'
1     NULL
1     '2013-03-03'      
2     '2013-02-23'      
2     '2013-04-12'      
2     '2013-05-02'   

我想从此表中获取信息:

And I would like to get from this table :

ID   DATE     

1     NULL    
2     '2013-05-02'   

这是我的查询:

select ID, max(DATE)
from test
group by ID

问题是MYSQL会忽略NULL值并返回我

Problem is that MYSQL ignores NULL values and returns me

ID   DATE     

1     '2013-03-03'   
2     '2013-05-02' 

在存在NULL的情况下如何将MAX设为NULL?

How can i do so when there is a NULL it takes the MAX as NULL?

推荐答案

试一下:

SELECT ID, case when MAX(DATE IS NULL) = 0 THEN max(DATE) END AS DATE
FROM test
GROUP BY ID;

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