I have two tables that hold information, one of properties and one of investors and I want to store investors that are interested in certain properties.
I am making a third linking table to store this information, but I'm not sure which is best practice, should I store one investor ID and many property ID's in one row (or one property ID to investor ID's) or should I do individual ones?
My problem is if I do individual ones the number of rows could easily go into the tens of thousands in a couple of months, but having many in one column will be a hefty number too.
Which is best practice? Small quantity of large data, or large quantities of small data?
(Also worth mentioning that I need to keep the data for reports so deleting them is out of the question.)