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It defines that the tuple in one relation that refers to another relation must refer to an existing tuple in that relation. This constraint is states on two relations (not essentially distinct). It uses a concept of foreign key and has been dealt with in more factors in the next unit.
Example
In the example given above, the value of C^ in every R tuple is matching with the value of C# in some S tuple. If a tuple has values (A6, B2, and C4) is added then it is invalid as referenced relation S doesn't contain C4. Therefore, it will be a violation of referential integrity constraint.
Increased parallelism : Since the replicated date has several copies a query can be distributed or can be answered from the smallest loaded site. Also, with more replicas you have
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Consider the relations EMPLOYEE(emp#, name) ASSIGNED_TO(project#, emp#) PROJECT(project#, project_name, chief) Express the subsequent queries in Relational Algebra (i) Ge
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Consider a table student (std_id, std_name, date_of_birth, percent_marks, dept_name). Write a QBE query to display names of Computer Science department students who have scored mo
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If the insertion violates one or more constraints, then two alternatives are available: Default option: - Insertion can be discarded and the reason of refusal can also be ex
Determine Which is not a consequence of concurrent operations? Ans: Update anomaly.
how map binary relation one to one
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