从分组的MySQL数据中获取最新日期

Question

我的数据库中有以下数据:

|NO | model | date     | 
+---+-------+----------+
|1  | bee   |2011-12-01|
|2  | bee   |2011-12-05|
|3  | bee   |2011-12-12|
|4  | tar   |2011-12-13|

我想获得每个模型组的最新日期:

| model | date     | 
+-------+----------+
| bee   |2011-12-12|
| tar   |2011-12-13|

我试过了:

SELECT model, date 
FROM doc
WHERE date ........????? //what is the next?
GROUP BY model

Answer 1

您在寻找每个型号的最大日期吗？

SELECT model, max(date) FROM doc
GROUP BY model

如果您正在寻找符合整个表格最大日期的所有型号......

SELECT model, date FROM doc
WHERE date IN (SELECT max(date) FROM doc)

Answer 2

您可以尝试在子查询中使用max(),如下所示:

SELECT model, date  
FROM doc 
WHERE date in (SELECT MAX(date) from doc GROUP BY model);

Answer 3

子查询给出日期.我们没有链接模型.所以下面的查询解决了这个问题.

如果有重复的日期/模型可以通过以下查询避免.

select t.model, t.date
from doc t
inner join (select model, max(date) as MaxDate from doc  group by model)
tm on t.model = tm.model and t.date = tm.MaxDate