Yearly and Monthly Repeat Reminders send on every cron for 24 hours

The current workaround for the Scheduled Reminders issue outlined in Scheduled annual membership reminders not sent after first year is to set a Schedule Reminder to repeat annually.

However - as per Eileen's comment in that thread, "We enabled yearly repeats and the reminders started going out hourly (every cron)."

We can confirm this behavior: if, as a workaround to resolve the issue where Schedule Reminders only send once, we set the Scheduled Reminder to repeat annually, the criteria that selects users is correct - but that same group of users will receive the Scheduled Reminder every time the Scheduled Reminder cron runs for a 24-hour period.

In our client's case, the Scheduled Reminder cron runs every 5 minutes, and this bug resulted in some very confused members who received 12 renewal reminders in a 60-minute period.

The problems are two-fold:

First, the code added to consider Monthly and Yearly renewal reminders is getting passed as a string and defaulting to '24' - which explains why the users are getting spammed for that particular period of time.

Second, the $havingClause was using the TIMEDIFF(number, datetime) function - and in newer versions of MySQL, that function returns NULL.

We've created a patch to address this; I'll attach it momentarily.