Composite foreign key that is optional
11467
Differences between MATCH FULL, MATCH SIMPLE, and MATCH PARTIAL?
103077
Cannot truncate table because it is being referenced by a FOREIGN KEY constraint?
26537
Possible to do a MySQL foreign key to one of two possible tables?
20394
Renaming foreign-key columns in MySQL
87556
How can I list all foreign keys referencing a given table in SQL Server?
133288
Using Foreign Key and References for ON DELETE CASCADE in mysql
55545
Find the Foreign Keys Associated with a Given Primary Key
74632
Query without having to specify table's schema
64024
Strings as Primary Keys in SQL Database
139603
Doctrine2: Best way to handle many-to-many with extra columns in reference table
47564
Foreign Key column mapped to multiple primary keys
96449
Database schema for entities with two possible owner/parent types?
33176
Can I have multiple primary keys in a single table?
5002
How to model an entity type that can have different sets of attributes?
74726
How can I add a foreign key when creating a new table?
101199
PostgreSQL foreign key not existing, issue of inheritance?
67443
How to prevent duplicate records being inserted with SqlBulkCopy when there is no primary key