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Tutorial-5 ANS - ITC114/ITC423 Tutorial-5 Section-A Write...

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ITC114/ITC423 Tutorial-5 Section-A – Write short answers 1. What is normalization and de-normalisation? A simplification process of database structure for evaluating and correcting table structures to minimize data redundancies and reduces data anomalies. 2. List different normalisation levels. a. First normal form (1NF) b. Second normal form (2NF) c. Third normal form (3NF) d. Boice-Codd Normal Form (BCNF) e. Fourth Normal Form (4NF) 3. What is a functional dependency in relation to normalisation process? Attribute ‘A’ determines attribute ‘B’ (that is ‘B’ is functionally dependant on ‘A’) if all of the rows of table that agree in value of attribute ‘A’ also agree in value for attribute ‘B’. A-->B Ex: Emp_No-->Emp_Name, Emp_Address 4. When a table is considered that it is in 1NF? Give an example. A table is considered to be in First Normal Form (1NF) when all key attributes are defined, there are no repeating groups in the table and all attributes are dependents on primary key. Ex: Employee(EMP_No, PROJ_NUM, PROJ_NAME, EMP_NAME, JOB_CLASS, CHG_HOURS, HOURS) 5. When a table is considered that it is in 2NF? Give an example. A Table is in second normal form (2NF) when it is in 1NF and it includes no partial dependencies and no attribute is dependent on only portion of primary key.
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