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Tagged with subtypes foreign-key
4
questions
0
votes
2answers
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Dealing with subtypes and supertypes in Database design
I'm currently doing a database project for a class and I am having some difficulty dealing the subtypes and supertypes.
This is the list of entities and their attributes:
Piece (PIECE_ID, Description)...
3
votes
2answers
943 views
Filtered foreign keys
I have two tables:
Contact (ID, Type);
Address (ID).
Is it possible to define a foreign key from Address (ID,'A') to Contact (ID,Type)?
3
votes
0answers
961 views
Supertype table with disjoint subtypes in MySQL
I want to have base parent table with few disjoint subtypes. To illustrate what I mean:
CREATE TABLE issues (
issue_id SERIAL PRIMARY_KEY,
issue_type CHAR(1) CHECK (issue_type IN ('B', 'F')),
...
4
votes
2answers
1k views
Two ways to define may-have-a (1..0-1) relationship
Today I have discovered for myself that may-have-a, one-to-zero-or-one, (1-0..1) relationship can be implemented in two different ways:
Let A be the "main" table (left side of ..) and B be the "...
