Question

我有一个简单的问题;我认为会有一个简单的解决方案。想象一下这样的表：

Name           Timestamp              Data
Bob            2011-01-01 01:00:00    Hi
Alice          2011-02-02 02:00:00    Hello
Alice          2011-03-03 03:00:00    Hello
Bob            2011-04-04 04:00:00    Bye
Charlie        2011-05-05 05:00:00    Cheese
Charlie        2011-06-06 06:00:00    Toast

我想要的只是能够运行一个查询，显示每个Name的最新条目。所以在上面的表格中，我想要一个像这样的输出：

Name           Timestamp              Data
Bob            2011-04-04 04:00:00    Bye
Alice          2011-03-03 03:00:00    Hello
Charlie        2011-06-06 06:00:00    Toast

按数据订购。我无法弄清楚如何做到这一点。我虽然可以做到：

SELECT DISTINCT(Name), timestamp, Data FROM Table ORDER BY Data

但这不起作用。非常感激任何的帮助，欢呼声。

Answer 1

使用此查询获取最后一个唯一值，

SELECT * FROM (select * from `table` order by date DESC) t group by name

Answer 2

select t1.* from table as t1
inner join (
select name,max(`timestamp`) as `timestamp`
from table
group by name) as t2
on t1.name = t2.name and t1.`timestamp` = t2.`timestamp`

Answer 3

SELECT DISTINCT Name, Timestamp, Data
FROM Table
WHERE Timestamp =
    (
     SELECT MAX(Timestamp)
     FROM Table AS tempTable
     WHERE Table.Name = tempTable.Name
    )

MySQL获取具有不同值的数据集

3 个答案: