Question

I need help designing a SQL table. Suppose I have cardnumber, cardtype, field1, field2, and field3.

Cardtype is an enumeration that can be “front”, “back”, or “both”.

1. I want to SELECT front.field1, front.field2, front.field3, back.field1, back.field2, back.field3 FROM some table or view WHERE cardnumber=XXX.

2. Most of the records will just contain field1, field2, field3, and “both” indicating that I should get front.field1 to be the same as back.field1, etc… when I SELECT. When “front” and “back” are different, I will need two rows with the same cardnumber, but one with “front” and the other with “back”, along with the appropriate field1…field3 for each side.

How do I design this table. Should I be using some VIEW of an INNER JOIN or a LEFT/RIGHT JOIN of some sort?

I’m open to different designs but I am hoping that any design will be easy to maintain (taking into account that most records will be one row containing “both”) and can satisfy my SELECT requirement.

Answer 1

Card
--------------------------------------------
CardNumber     CardType_id    field1     etc

CardType
--------------------------------------------
ID     Description


SELECT
     Card.*,
     CardType.Description
FROM Card
          INNER JOIN CardType
                ON Card.CardType_id = CardType.ID
WHERE CardType.Description = 'your description value'