Define assertions in sql, Database Management System

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Define Assertions in SQL

a. An assertion is a predicate that is expressing a condition we wish the database to always satisfy. 

b. Domain constraints, functional dependency and referential integrity are unique forms of assertion.

c. In which a constraint cannot be expressed in these forms, we use an assertion, for example 

  • Making sure the sum of loan amounts for each branch is less than the sum of all account balances at the branch.
  • Making sure every loan customer keeps a minimum of $1000 in an account.

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