52.  Spurious tuples may occur due to

       i. Bad normalization 

      ii. Theta joins

     iii. Updating tables from join

            a) i & ii                         b) ii & iii

            c) i & iii                                    d) ii & iii

 

 (a) i & iii  because  theta joins are joins made on keys that are not primary keys.

 

53.  A B C is a set of attributes. The functional dependency is as follows

      AB  ->   B

      AC ->    C

         C ->    B

            a) is in 1NF

            b) is in 2NF

            c) is in 3NF

            d) is in BCNF

 

 (a) is in 1NF since (AC)+ = { A, B, C} hence AC is the primary key. Since         C       B is a FD given, where neither C is a Key nor B is a prime attribute, this it is not in 3NF. Further B is not functionally dependent on key AC thus it is not in 2NF.  Thus the given FDs is in 1NF.

 

54.  In mapping of ERD to DFD

            a) entities in ERD should correspond to an existing entity/store in DFD

            b) entity in DFD is converted to attributes of an entity in ERD

            c) relations in ERD has 1 to 1 correspondence to processes in DFD

            d) relationships in ERD has 1 to 1 correspondence to flows in DFD

 

 (a) entities in ERD should correspond to an existing entity/store in DFD

 

55.  A dominant entity is the entity

            a) on the N side in a 1 : N relationship

            b) on the 1 side in a 1 : N relationship

            c) on either side in a 1 : 1 relationship

            d) nothing to do with 1 : 1 or 1 : N relationship

 

(b) on the 1 side in a 1 : N relationship

 

56.  Select  ‘NORTH’, CUSTOMER From CUST_DTLS Where REGION = ‘N’ Order By

CUSTOMER Union Select  ‘EAST’, CUSTOMER From CUST_DTLS Where REGION = ‘E’ Order By CUSTOMER

The above is

            a) Not an error

            b) Error – the string in single quotes ‘NORTH’ and ‘SOUTH’

            c) Error – the string should be in double quotes

            d) Error –  ORDER BY clause

 

(d)  Error – the ORDER BY clause. Since ORDER BY clause cannot be used in UNIONS

 

57.  What is Storage Manager? 

It is a program module that provides the interface between the low-level data stored in database, application programs and queries submitted to the system. 

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