SQL: Get grouping range data

Requirements: Get the first 30 days of data for each live_id.
Note!!! This efficiency is very low, do not run on the line, careful fryer
Method 1:
SELECT a.* from User_live a
Left joins User_live B on a.live_id=b.live_id and A.create_time<b.create_time
GROUP by A.live_id,a.watch_num,a.create_time have COUNT (b.live_id) <29 ORDER by A.live_id,a.create_time ASC

Method 2:
Select a. From user_live a WHERE > (SELECT COUNT () from user_live
WHERE live_id = a.live_id and Create_time > A.create_time) ORDER by A.live_id,a.create_time

SQL: Get grouping range data