小白一枚,问下这段语句什么意思
小白一枚,想请问主要是 data_format后面的括号在sql中代表什么意思
select distinct
date_format(from_unixtime(a.ctime),'%Y%m%d') as "激活日期"
,a.open_udid as "设备标识"
,a.device_type as "设备类型"
,m.uid as "用户ID"
,u.mobile as "电话"
,mdd.name as "激活地点"
,m.lat as "经度"
,m.lng as "纬度"
, (case when back.open_udid is not null then '留存'
else '未留存'
end) as "是否留存"
from device.source_short_url_latest a
JOIN omc.short_url_map b
on a.short_name=b.des