I have students table and they must pay every month, I have start_day and end_day.
For example:
start_day = "2018-01-01";
end_day = "2018-03-30";
I want to send an SMS 3 days before pay day. I don't know how to fetch those dates in this interval.
select user_id from schema.table where end_day between
subdate(current_date, interval 3 day) and subdate(current_date, interval 2 day);
A bad way to do this would be : where date(end_day) = current_date-3
Why I don't prefer the bad way (although it looks simple):
joins and where clause. This'll prevent indexes (if any) from being used and will give you nightmares in terms of performance.- is an arithmetic operator. It's generally not a good practice to use +/- with dates. Use the functions intended to manipulate dates. (subdate, date_add, date_sub etc)