mysql为每个关系选择最高记录

Question

我有一张包含以下数据的表格：

=========================================
| name        |  version   | project_id |
=========================================
| foo         |           1|           1|
| new foo     |           2|           1|
| bar         |           1|           2|
=========================================

如何编写返回每个产品的最高版本记录的查询？从上表中，我想得到以下结果：

=========================================
| name        |  version   | project_id |
=========================================
| new foo     |           2|           1|
| bar         |           1|           2|
=========================================           

Answer 1

测试表

查询

结果

赢得我的朋友：）

Answer 2

SELECT
  t1.name, t1.version, t1.project_id
FROM
  tablename t1
JOIN
  (SELECT max(version) as version, project_id FROM tablename GROUP BY project_id) t2
ON t1.project_id = t2.project_id AND t1.version = t2.version

Answer 3

最简单的方法如下所示

select substring_index(group_concat(`name` order by version),',',-1) as `name`,
max(version) as version,project_id 
from your_table 
group by project_id 
order by projec`t_id;