SELECT userinfo.id, user_name, role, adm_regionid, region_name , create_time FROM userinfo LEFT JOIN region ON userinfo.adm_regionid = region.id
结果：
设置显示默认值：
复制代码 代码如下:
SELECT userinfo.id, user_name, role, adm_regionid, IFNULL(region_name,0) as region_name, create_time FROM userinfo LEFT JOIN region ON userinfo.adm_regionid = region.id
