What Referential integrity means?

• Do not enter a value in the foreign key field of a child table if that value does not exist in the primary key of the parent table

• Do not enter a value in the primary key field of the child table if that value does not exist in the primary key of the parent table

• Do not enter a value in the foreign key field of a parent table if that value does not exist in the primary key of the child table

• All of above

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