UGC NET JULY 2018 (Computer Science And Applications Paper-II) (Question 61-64)

UGC NET JULY 2018 (Computer Science And Applications Paper-II) (Question 61-64)

Q 61. In RDBMS, which type of Join returns all rows that satisfy the join condition?
 
(A) Inner Join
(B) Outer Join
(C) Semi Join
(D) Anti Join

Answer : (B) Outer Join

Explanation : Outer Join return all rows that satisfy condition from both the participating relations. An outer join extends the result of a simple join. An outer join returns all rows that satisfy the join condition and also returns some or all of those rows from one table for which no rows from the other satisfy the join condition. 

 

Q 62. Consider a relation book (title, price) which contains the titles and prices of different books. Assuming that no two books have the same price, what does the following SQL query list ?

Select title
from book as B
where (select count ( * )
    from book as T
    where T.price > B.price) < 7

(A) Titles of the six most expensive books.
(B) Title of the sixth most expensive books.
(C) Titles of the seven most expensive books.
(D) Title of the seventh most expensive books.

Answer :  (C) Titles of the seven most expensive books.

Q 63.  In a Hierarchical database, a hashing function is used to locate the ________.

(A) Collision
(B) Root
(C) Foreign Key
(D) Records

Answer :  (B) Root

Explanation :  A Data Model is the methodology used by a particular DBMS to organize and access the data.

Hierarchical, Network and Relational Model are the three popular data models. 

However, the relational model is more widely used.

Hierarchical Model :

• The hierarchical model was developed by IBM in 1968.
  
• The data is organize in a tree structure where the nodes represent the records and the branches of the tree represent the fields.
  
• Since the data is organized in a tree structure, the parent node has the links to its child nodes.
  
• If we want to search a record, we have to traverse the tree from the root through all its parent nodes to reach the specific record. Thus, searching for a record is very time consuming.
  
• The hashing function is used to locate the root.
  

Q 64. Relations produced from E – R Model will always be in ________.

(A) 1 NF
(B) 2 NF
(C) 3 NF
(D) 4 NF

Answer :  (A) 1 NF