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Tuesday, September 26, 2017

HSST Computer Science / Application


Q.The operation which is not considered a basic operation of relational algebra is
(A)    Join.                                               (B)    Selection.
 (C)    Union.                                           (D)    Cross product.

Answer: A
An SQL join clause combines columns from one or more tables in a relational database. It creates a set that can be saved as a table or used as it is. AJOIN is a means for combining columns from one (self-table) or more tables by using values common to each.

Q1. ER modelling technique is
a.tree structure
b.top down
c.bottom up
d. right left approach

Answer : b.top down
A graphical technique for understanding and organizing the data independent of the actual database implementation


Q2. The descriptive property possessed by each entity set is _________ .
a) Entity
b) Attribute
c) Relation
d) Model

Answer:  b) Attribute

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