MySQL GROUP BY 和 ORDER BY 的使用

Question

我有一张人表，每个人都有访问次数和优先级:

ID | NAME          |  VISITS | PRIORITY
---------------------------------------
 1 |     John      |    1    |   0
 2 |     Joe       |    2    |   1
 3 |     Peter     |    1    |   1
 4 |     Sara      |    0    |   2  
 5 |     Phillip   |    5    |   0
 6 |     Bob       |    3    |   1
 7 |     Andrew    |    4    |   2

只有某些允许的优先级:(0,1,2)

如何创建一个查询，根据访问次数(从最低开始)为我提供在相应优先级组内的人员？

所以结果应该是这样的:

ID | NAME          |  VISITS | PRIORITY
---------------------------------------
 1 |     John      |    1    |   0
 2 |     Philip    |    5    |   0
 3 |     Peter     |    1    |   1
 4 |     Joe       |    2    |   1  
 5 |     Bob       |    3    |   1
 6 |     Sara      |    0    |   2
 7 |     Andrew    |    4    |   2

我想必须使用 GROUP BY 子句，但我不确定如何使用它。

Answer 1

你刚刚试过 ORDER BY:

select id, name, visits, priority
from people
order by priority, visits

参见 SQL Fiddle with Demo