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SQL Server Limit Validation Request

I have a table in which payments are stored, and you want to make sure that the payment method is a credit card, then the card type field should be IN ("Visa", "MasterCard", "Discover", "American Express"), however if the payment method is not a credit card, then the card type field must be NULL.

Will the check constraint allow me to use this operator:

(method = 'CC' AND cardType IN ('Visa', 'MasterCard', 'Discover', 'American Express'))
OR
(method != 'CC' AND cardType = NULL)

I could completely abandon this, since the restrictions should probably be used only for checking 1 field (not sure).

Also, if such approval is allowed, is there likely to be an adverse effect?

Edit: I plan, after all, to create a cardType field and have cardType in our payment table as a foreign key ... this is just what I am thinking of doing at the same time

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1 answer

Why not just use a foreign key for another table and allow null?

It would be even better to get a card type code in another table and save the key to it.

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Source: https://habr.com/ru/post/1712882/

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