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Given two tables R1(x, y) and R2(y, z) with 50 and 30 number of tup...

  • Q.

    Given two tables R1(x, y) and R2(y, z) with 50 and 30 number of tuples respectively. Find maximum number of tuples in the output of natural join between tables R1 and R2 i.e. R1 * R2? (*. Natural Join)

  • filter_dramaExplanation
    Answer is : D

    Concept:

    A natural join is based on common attributes or common columns to join two tables or relations.

    Explanation:

    Consider an example, suppose there are two tables Employee(Eid, Ename) consists of 5 tuples and department(Eid, Did) consists of 3 tuples only.

    Eid

    Ename

    1

    E1

    1

    E2

    1

    E3

    1

    E4

    1

    E5

     

    Eid

    Did

    1

    D1

    1

    D2

    1

    D3

     

    Natural join of employee and department(Employee * Department) gives:

    5 × 3 = 15

    So, maximum number of tuples in natural join are from the relation having minimum tuples. So, in given question, R2 contains 30 tuples, so , maximum number of tuples in the output of natural join between tables R1 and R2 i.e. R1 * R2 = 50 × 30 = 1500.

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Similar Questions

  • 1.

    Which operation are allowed in a join view:

  • filter_dramaExplanation
    Answer is : D

    The DELETE statement is used to delete rows in a table. The UPDATE statement is used to update existing records in a table. The INSERT INTO statement is used to insert new records in a table.

  • 2.

    Consider the following two tables and four queries in SQL.

    Book (isbn, bname), Stock (isbn, copies)

    Query 1:

    SELECT B.isbn, S.copies
    FROM Book B INNER JOIN Stock S
    ON B.isbn = S.isbn;
    

    Query 2:

    SELECT B.isbn, S.copies
    FROM B B LEFT OUTER JOIN Stock S
    ON B.isbn = S.isbn;

    Query 3:

    SELECT B.isbn, S.copies
    FROM Book B RIGHT OUTER JOIN Stock S
    ON B.isbn = S.isbn;

    Query 4:

    SELECT B.isbn, S.copies
    FROM B B FULL OUTER JOIN Stock S
    ON B.isbn = S.isbn;

    Which one of the queries above is certain to have an output that is a superset of the outputs of the other three queries?

  • filter_dramaExplanation
    Answer is : D

    In SQL the FULL OUTER JOIN combines the results of both left and right outer joins and returns all (matched or unmatched) rows from the tables on both sides of the join clause.

    So, option (D) is correct.

  • 3.

    Which product is returned in a join query have no join condition:

  • filter_dramaExplanation
    Answer is : B

    A Cartesian coordinate system is a coordinate system that specifies each point uniquely in a plane by a pair of numerical coordinates.

    A CROSS JOIN or CARTESIAN JOIN returns the Cartesian product of an available set of records from multiple joined tables. Thus, this join would equate to an inner join in which the join-condition always evaluates to either True or wherever the join-condition is not present in the statement.

  • 4.

    A condition is referred to as __________

  • filter_dramaExplanation
    Answer is : B

    An SQL join clause combines records from two or more tables in a database. It creates a set that can be saved as a table or used as it is. A JOIN is a means for combining fields from two tables by using values common to each.

  • 5.
    SELECT *
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    The above query is equivalent to

  • filter_dramaExplanation
    Answer is : A

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