mysql - 如何使用矩阵顺序选择顶部不同的值

Question

我有一张这样的 table

我想获取每个表中具有最短响应时间的行

我尝试过这个查询:

select tablename,
       index1, 
       index2, 
       min(responsetime) 
from   tableconf 
group by tablename 
order by responsetime asc

但它没有给出我想要的

我想要的输出是

+------------------+------------------+--------+--------------+
|    tablename     |     index1       | index2 | responsetime |
+------------------+------------------+--------+--------------+
| salesorderheader | TotalDue         | NULL   |       6.1555 |
| salesterritory   | Name             | NULL   |     11.66667 |
| store            | BusinessEntityId | Name   |       3.6222 |
| previous         | previous         | NULL   |      5.03333 |
| NONE             | NONE             | NULL   |          5.6 |
+------------------+------------------+--------+--------------+

我应该使用什么查询来获取我想要的输出

Answer 1

选择每个表名称的最短日期。对这些使用 IN 子句来获取行:

select *
from tableconf 
where (tablename, responsetime) in
(
  select tablename, min(responsetime)
  from tableconf 
  group by tablename
);