Can a Foreign Key Reference Multiple Tables in a Relational Database?

Can a Foreign Key Point to Multiple Tables?

Setting foreign key constraints typically involves selecting a single target table. However, in the context of polymorphic relationships, a single table may have connections with multiple other tables.

Polymorphic Relationships and Foreign Keys

In polymorphic relationships, a table (e.g., images) maintains a relationship with one of several other tables (e.g., subordinates or products). This is achieved through a column (person_type) that identifies the specific table to which the foreign key should point.

Answer

Unfortunately, no. Foreign key constraints only allow references to a single parent table. This means that you cannot create a foreign key that points to multiple tables simultaneously.

Alternatives

However, there are ways to simulate this behavior using other techniques, such as:

• Discriminator columns: Add a column to the parent table that identifies the type of child table.
• Union tables: Create a single table that contains the combined data from all related tables.

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