sql的执行顺序,外连接注意点
select date(oi.pay_time) as event_date, count(distinct oi.device_id) as uv, count(*) as order_total, (select platform from app_event_log_start_up as su where su.uid = oi.user_id and date(su.event_time) = '$day' limit 1) as os, pol.user_id from order_info oi left join points_ops_log pol on pol.user_id = oi.user_id and date(pol.create_time) = '$day' and pol.ops = 'obtain' and pol.worker in ('xx', 'xx', 'xx') where date(oi.pay_time) = '$day' and pol.user_id is null group by os having os is not null;