SELECT *,
(SELECT city
FROM province_city_CN
WHERE id = dealer_VIEW.province) AS 省份
,
(SELECT city
FROM province_city_CN
WHERE id = dealer_VIEW.city) AS 城市
FROM dealer_VIEW能否优化下??
(SELECT city
FROM province_city_CN
WHERE id = dealer_VIEW.province) AS 省份
,
(SELECT city
FROM province_city_CN
WHERE id = dealer_VIEW.city) AS 城市
FROM dealer_VIEW能否优化下??
a.*,
b.city AS 省份,
c.city AS 城市
FROM
dealer_VIEW a,
province_city_CN b,
province_city_CN c
where
a.province=b.id and a.city=c.id
select *,t2.city as 省份,t3.city as 城市
from dealer_VIEW t1 left join province_city_CN t2 on t1.province = t2.id
left join province_city_CN t3 on t1.city = t3.id
from dealer_VIEW dv
inner join province_city_CN p
on p.id = dv.province
inner join city c
on c.id = dv.city
city as 省份,
city as 城市
FROM dealer_VIEW是不是这样?
但速度提升并不明显.
from dealer_VIEW
left join province_city_CN on dealer_VIEW.province = province_city_CN.id
left join province_city_CN on dealer_VIEW.city = province_city_CN.id