database design help please

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database design help please

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gf-350872

Posted Wednesday, January 23, 2013 7:44 PM

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Last Login: Sunday, January 27, 2013 9:34 PM
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Hi I am having some trouble on how to normalize some tricky tables.

Basically it is a recurrence event table that can either be daily, weekly, monthly or yearly.

I have made it so each recurrence row in the header table can have one id for either daily, weekly, monthly or yearly. This id corresponds to the appropriate table. Each table has different structures.

So here is an example of what I have.

Table: Recurrence
Columns: RecurrenceId (PK), RecurrenceDailyId(FK), RecurrenceWeeklyId (FK),
RecurrenceMonthlyId (FK), RecurrenceYearlyId (FK)

Table: RecurrenceDailyId
Columns: RecurrenceDailyId(PK), EveryDays, DayOfWeek etc

Table: RecurrenceWeeklyId
Columns: RecurrenceWeeklyId(PK), EveryWeeks, TimesAWeek etc

etc

What is the best way to create this structure so it is normalized? am I on the right path?

Post #1410874

Grant Fritchey

Posted Thursday, January 24, 2013 8:14 AM

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Last Login: Yesterday @ 3:40 PM
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Nah, I'd say you're digging a bit of a hole. Instead how about something like

Recurrence ... whatever columns are unique to the recurrence
RecurrenceSchedule ... just a listing of each of the types, daily, monthly, etc., and any unique values to them
RecurrenceScheduleType ... a join between the schedule and the recurrance. Probably make the primary key the two tables keys, but put a unique constraint on the Recurrence key in addition so that a recurrence can only have one type.

The other method involves a lot of null values and joins to tables without data. This will ensure you always get data back.

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Post #1411161

gf-350872

Posted Sunday, January 27, 2013 9:53 PM

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Thanks

Post #1412174

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