Question

Which rule should not observe, when the referential integrity is enforced. *

You can't delete a record from a primary table if matching records exist in a related table.
You can't change a primary key value in the primary table, if that record has related.
You can set the composite key in both the tables.
You can't enter a value in the foreign key of the related table that doesn't exist in the primary key of the primary table.​

Answer 1

Answer:

lock and key model proposed by Emil Fischer for enzymes

Explanation:

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