mysql case when 使用方法

应用场景:表里面有id,level和village_id,town_id,county_id,city_id,province_id等几个字段,要求是如果是5级的话,则取village_id 作为address_id,4级则取town_id 作为address_id,注意:address_id是你自定义的名字

select * ,
CASE
when level=5 THEN
village_id
when level=4 THEN
town_id
when level=3 THEN
county_id
when level=2 THEN
city_id
when level=1 THEN
province_id
END 'address_id'
from big_position  where id in (51719,51806,51860,51938,52997,58394,59933,80148) order by field(id,51719,51806,51860,51938,52997,58394,59933,80148)

mysql case when 使用方法

select * from information_schema.columns where table_name='zh_farm_device'    查看表结构