Re: How to normalize?
Hello, thank you for reply. I tried to explain my question, draw a simple DB. But it seems you even not tried to watch this screenshot. You prefer SQL query text from mysql workbench instead of screenshot?
There are 3 tables with expenses and just one table with payment records.
This payment table contains 3 FK to each of expenses tables.
I can not merge 3 expenses tables into one, don't want to make flat table.
But 3 foreign keys in payments table is also not ok.
There is additional control needed to be ensured that the some payment is linked with proper expense table.
Anomalies could be here : for example, one payment record can have 2 active foreign keys or all 3.
But just 1 of 3 is allowed by logic.
Few records with same FK value could be in sequence, but not a record with 2 or 3 filled FK in same time.
I want to get a solutions. Please.
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Re: How to normalize?
May 02, 2021 01:02PM
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