sql：row_number() over(partition by xxxxxxxxxx order by yyyyyyyyyyyyy)
xxxxxxxxxx：分组字段；yyyyyyyyyyyyy：排序字段
select
row_number() over(partition by d.area_code order by a.customer_name),
a.customer_name, d.area_code
from jc_customer as a
left join jc_province as b on a.province = b.province_name
left join jc_city as c on a.city = c.city_name and b.province_code = c.province_code
left join jc_area as d on a.area = d.area_name and c.city_code = d.city_code
order by d.area_code