What do you understand by self-referencing constraints?

1.	What do you understand by self-referencing constraints?
Answer» Self-referencing constraints are USED for restricting changes that can be possibly made to a primary key using a FOREIGN key. For achieving this, the foreign keys need to define the DELETE-CASCADE rule which states that in CASE the RELATIONSHIP for DELETE rule is defined as CASCADE, if one ROW is changed or deleted, then other rows in the table are recursively deleted.

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