我有适用于美国邮政编码的mysql表
id | zip_code | city | State
1 | 99553 | Akutan | Alaska
2 | 99571 | Cold Bay | Alaska
3 | 99583 | False Pass | Alaska
4 | 36006 | Billingsley| Alabama
5 | 36008 | Booth | Alabama
6 | 36051 | Marbury | Alabama
.....
我想使用单个选择MySQL查询来为每个州仅获取2个城市 因此最终结果如下表所示
id | zip_code | city | State
1 | 99553 | Akutan | Alaska
2 | 99571 | Cold Bay | Alaska
4 | 36006 | Billingsley| Alabama
5 | 36008 | Booth | Alabama
答案 0 :(得分:1)
如果您正在运行MySQL 8.0,则可以使用row_number()
:
select id, zip_code, city, state
from (
select t.*, row_number() over(partition by state order by zip_code) rn
from mytable t
) t
where rn <= 2
在早期版本中,您可以使用相关子查询进行过滤:
select t.*
from mytable t
where (
select count(*)
from mytable t1
where t1.state = t.state and t1.zip_code <= t.zip_code
) <= 2