请教下mysql多表联查后怎么根据时间统计数量

Question

 

Answer 1

select time,sum(num_log),sum(num_dev),sum(num_user)

（

select   date(time) as time,sum(1) as num_log,0 as num_dev,0 as num_user    from user_log group by date(time)

union all

select   date(time) as time,0 as num_log,sum(1) as num_dev,0 as num_user    from user_dev group by date(time)

union all

select   date(time) as time,0 as num_log,sum(1) as num_dev,0 as num_user    from user_user where status='1' group by date(time)

） group by time