Mysql Event Scheduler using local variable - mysql

Question

I am trying to create a report schedule in mysql, but the query depends on the local variable fdate. How can I have mysql load the fdate variable and then run the query in the 2nd event? Thanks
CREATE EVENT fdate
ON SCHEDULE
EVERY 1 DAY
starts '2018-03-26 07:30:00'
Do
set #fdate = 2018031; #EOM prior month
create event report_1 on SCHEDULE
EVERY 1 day
starts '2018-03-26 07:31:00'
DO
<Here is the Query depending up fdate>

Answer 1

I think each event executes in a new session, and user-defined variables have session scope. So you can't really use those variables in events and have their value survive from one event execution to another.
Here's a test to show it:
mysql> create table log ( i int );
mysql> create event e on schedule every 1 minute do
-> insert into log set i = #a := coalesce(#a+1, 1);
If the #a variable retains its value from one event execution to the next, we'll get a series of incrementing values in my log table.
A few minutes later, we see that we don't get incrementing values. Each execution starts the counter over at 1.
mysql> select * from log;
+------+
| i |
+------+
| 1 |
| 1 |
| 1 |
+------+
But you can DECLARE a local variable, and use it in a compound statement body for an event.
CREATE EVENT fdate
ON SCHEDULE
EVERY 1 DAY
STARTS '2018-03-26 07:30:00'
DO BEGIN
DECLARE fdate INT;
SET fdate = DATE_FORMAT(LAST_DAY(CURDATE() - INTERVAL 1 MONTH), '%Y%m%d');
# following query uses fdate
END