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Unit 7: Relational Database Design
7.11 Self Assessment Notes
Fill in the blanks:
1. The relational model was proposed by ...............................
2. When a single constraint is established between two sets of attributes from the database it
is called .................................
3. The first concept of normalisation was proposed by Mr. Codd in ........................
4. ............................ is defined using the concept of the join dependencies.
5. Functional dependencies (FD) are type of constraint that is based on ..........................
6. The weak entity has only a ............................. key.
7. The ............................. is convenient for representing an initial, high-level database design.
8. An entity set is mapped to a relation in a .............................way.
9. A ............................ always participates in a one-to-many binary relationship and has a key
constraint and total participation.
10. The ................................. is trivial since it results in no constraints being placed on the
relation.
7.12 Review Questions
1. Explain with examples the problems cause due to redundancy of data in tables or relations.
2. Define functional dependency. Give example.
3. Describe various features of relational database.
4. Describe with examples the techniques used for reducing the redundancy of data in tables.
5. Sketch with examples the differences between the Third Normal Form (3NF) and Boyce
Codd Normal Form.
6. Explain why a relation table is subjected to advanced normalizations?
7. Define Multivalued Dependencies. Give Examples. Explain how are they eliminated?
8. What do you mean by join dependencies?
9. Consider the relation R (A, B, C, D, E) with functional dependencies
A B,C
CD D
B D
E A
List the candidates key for R. Give a lossless dependency preserving decomposition of R.
into 3 NF and explain it briefly.
10. Describe the rules of functional dependencies.
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