SQL insert into select with parameter for using with event scheduler - mysql

Question

Hello I would like to make event for my application that works by insert new 3 record for 1 userID every midnight so the quantity of rows must have
n x 3 n is userIDs
+---------+-----------+-------+------------+------+----------+-------------+-------+
| userID | userNAME | chaID | chaNAME | goal | gender | row_number | dummy |
+---------+-----------+-------+------------+------+----------+-------------+-------+
| 1 | Nanyang | 1 | blahblah | 1 | 2 | 1 | 1 |
| 1 | Nanyang | 21 | something | 1 | 2 | 2 | 1 |
| 1 | Nanyang | 2 | anything | 1 | 2 | 3 | 1 |
| 2 | Julie | 3 | x | 2 | 1 | 1 | 2 |
| 2 | Julie | 12 | y | 2 | 1 | 2 | 2 |
| 2 | Julie | 23 | z | 2 | 1 | 3 | 2 |
| 3 | Kingkong | 4 | a | 1 | 2 | 1 | 3 |
| 3 | Kingkong | 5 | b | 1 | 2 | 2 | 3 |
| 3 | Kingkong | 6 | c | 1 | 2 | 3 | 3 |
+---------+-----------+-------+------------+------+----------+-------------+-------+
the row_number will be looped until they're <= 3
from my written ..
set #num := 0, #type := ‘';
CREATE TABLE random
as
(
SELECT
*
FROM (
select userID,userNAME, chaID, chaNAME,goal,gender,
#num := if(#type = userID, #num +1,1) as row_number,
#type := userID as dummy
from userchar
order by userID
) as x where x.row_number <= 3)
Anyway I used to try to create table with Select the first/least/max row per group in SQL
and it works very well and get the result like i shown. then I need to insert into in event instead of create table so i got this code below.. because I can't use SET #parameterfor insert
INSERT INTO random(userID, userNAME, chaID, chaNAME, goal, gender,row_number,dummy,status)
select *
from (select userID, userNAME, chaID, chaNAME, goal, gender,
(#num := if(#type = userID, #num +1,1)
) as row_number,
userID as dummy,
#stat as status
from hb_usercha u cross join
(select #type = '', #num := 0, #stat := '') params
order by userID,rand()
)
where row_number <= 3;
and this is a result what I got
+---------+-----------+-------+------------+------+----------+-------------+-------+
| userID | userNAME | chaID | chaNAME | goal | gender | row_number | dummy |
+---------+-----------+-------+------------+------+----------+-------------+-------+
| 1 | Nanyang | 1 | blahblah | 1 | 2 | 1 | 1 |
| 1 | Nanyang | 21 | something | 1 | 2 | 1 | 1 |
| 1 | Nanyang | 2 | anything | 1 | 2 | 1 | 1 |
| 1 | Nanyang | 3 | s | 2 | 1 | 1 | 1 |
| 1 | Nanyang | 12 | o | 2 | 1 | 1 | 1 |
| 1 | Nanyang | 23 | m | 2 | 1 | 1 | 1 |
| 1 | Nanyang | 4 | e | 1 | 2 | 1 | 1 |
| 2 | Julie | 5 | xoxo | 1 | 2 | 1 | 2 |
| 2 | Julie | 6 | xxx | 1 | 2 | 1 | 2 |
+---------+-----------+-------+------------+------+----------+-------------+-------+
.
.
.
.
It seems row_number loop isn't working
And I have no idea what's happening
Both code are same just changed parameters path
So It would be very good if someone can explain to me
Thank you so much

Answer 1

Assuming you want to do it for all users exists in user_char table.
Using Union all to get 3 records of each user and store the result in temporary table.
DELIMITER $$
CREATE EVENT `event_run_midnight` ON SCHEDULE EVERY 24 HOUR STARTS '2016-02-09 00:00:00' ON COMPLETION NOT PRESERVE ENABLE DO
BEGIN
drop temporary table if exists temp_users_1;
create Temporary table temp_users_1
select users.*,#row_num:=#row_num+1 as row_num,userID as dummy
from(
select * from user_char
union all
select * from user_char
union all
select * from user_char
) as users,(select #row_num:=0) as row_number
order by UserID;
/*
Copy temp table data to other temp table as MySQL
not allows to use same temp table in single query.
*/
drop temporary table if exists temp_users_2;
create Temporary table temp_users_2
select * from temp_users_1;
-- final query which returns desired output :
INSERT INTO random(userID, userNAME, chaID, chaNAME, goal, gender,row_number,dummy)
Select usr.userID,
usr.userNAME,
usr.chaID,
usr.chaNAME,
usr.goal,
usr.gender,
usr.row_num-usr_grp.min_row_num+1 as row_number,
usr.userID as dummy
from temp_users_1 usr
inner join (
Select userID,
min(row_num) as min_row_num
from temp_users_2 group by userID
) usr_grp on usr.UserID=usr_grp.userID
where usr.row_num-usr_grp.min_row_num+1 <=3; -- Condition to show only 3 records of each users.
END$$
DELIMITER ;
Updates:
1- Added Event Creation.
2- Assuming you are inserting repetitive user records into table name random.
3- This Event will execute daily at 12:00 AM.
Note:
1- You may have to change the table names if tables names are different as in answer.
2- Make sure that you have enabled MySQL Event scheduler in Configuration file otherwise event will not run automatically.
Here is the link which help you enabling MySQL event scheduler if not enabled:
http://geeksterminal.com/enable-mysql-event-scheduler-status/1711/