SQL Syntax Reference : CASCADE
 
CASCADE
Remarks
If you specify CASCADE when creating a Foreign Key, PSQL uses the DELETE CASCADE rule. When a user deletes a row in the parent table, PSQL deletes the corresponding rows in the dependent table.
Use caution with delete cascade. PSQL allows a circular delete cascade on a table that references itself. See examples in Delete Cascade in Advanced Operations Guide.
See Also
ALTER TABLE
CREATE TABLE