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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.
Describe five main functions of a database administrator. Ans: A database administrator (DBA) is a person who is accountable for the environmental aspects of a database. Genera
write a short note on participation role? Participation role: roles are indicating in E-R diagram by labelling the lines that connect diamonds to rectangles.
One-to-many : An entity in A is related with any number of entities in B. An entity in B is related with at the most one entity in A. Example: Relationship between faculty and d
Two-way Associations Mostly, associations are travel in both directions, although not usually with same frequency. There are three approaches for the implementation. In
Extend your CREATE TABLE statement from problem 3 with referential integrity constraints. Updates and deletes on related rows are restricted. 6. From examination of the sample data
Data Manipulation Language Data manipulation language (DML) describes a set of commands that are used to query and change data within existing schema objects. In this case comm
Describes the several relationship constraints through giving suitable example? Constraints on relationships: There are two kinds of constraints on relationships. 1) Mapping
List the Armstrong's axioms for functional dependencies. What do you understand by soundness and completeness of these axioms? Ans: The Armstrong's axioms are: F1:
need a DBMS system on any data for assignment.
Let us now make the E-R diagram for the student database as per the explanation given in the previous section. We can also states the overall logical structure of a database usi
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