Possible to combine these 2 database columns into 1?

Question

I have a recurring event schema that has a RecurrenceType and a RecurrenceMultiple column. The RecurrenceType is a foreign key to a table that has these options (1) No Recurrence (2) Daily (3) Weekly (4) Monthly. RecurrenceMultiple is an integer that indicates what multiple of the recurring time frame each event occurs. a few examples

• RecurrenceType=1, RecurrenceMultiple=1 : One time only
• RecurrenceType=2, RecurrenceMultiple=1 : Every day
• RecurrenceType=3, RecurrenceMultiple=1 : Every week
• RecurrenceType=3, RecurrenceMultiple=2 : Every other week
• RecurrenceType=4, RecurrenceMultiple=1 : Every month
• RecurrenceType=4, RecurrenceMultiple=3 : Every 3rd month
• RecurrenceType=4, RecurrenceMultiple=12 : Yearly

I'd like to somehow combine these two columns in a way that I can infer the RecurrenceType allowing me to ditch the lookup table. I can't think of a good way to do this though and avoid collisions.

Answer 1

This is the approach I've decided to use

A single column RecurrenceFrequency can be used if it's assumed that 0 means no recurrence, positive values mean a timespan of X days and negative values mean a timespan of X months

• 0 : One time only
• 1 : Every day
• 7 : Every week
• 14 : Every other week
• -1 : Every month
• -3 : Every 3rd month
• -12 : Yearly