ISRO2008-33

Question

The join operation can be defined as

• A. a cartesian product of two relations followed by a selection
• B. a cartesian product of two relations
• C. a union of two relations followed by cartesian product of the two relations
• D. a union of two relations

Answer 1

Answer will be option A.

Join is a combination of a Cartesian product followed by a selection process. A Join operation pairs two tuples from different relations, if and only if a given join condition is satisfied.

reference:: http://www.tutorialspoint.com/dbms/database_joins.htm

Answer 2

Answer : A

Join is a combination of a Cartesian product followed by a selection process. A Join operation pairs two tuples from different relations, if and only if a given join condition is satisfied.

Answer 3

ans is (a)

A 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. A JOIN is a means for combining columns from one (self-table) or more tables by using values common to each. ANSI-standard SQL specifies five types of JOIN: INNER, LEFT OUTER,RIGHT OUTER, FULL OUTER and CROSS. As a special case, a table (base table, view, or joined table) can JOIN to itself in a self-join.

https://en.wikipedia.org/wiki/Join_(SQL)