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Which of the following Relational Algebra operations can be used wh...

  • Q.

    Which of the following Relational Algebra operations can be used when you want to keep all the tuples of the first relation irrespective of whether or not they have matching tuples in the second relation?

  • filter_dramaExplanation
    Answer is : B

    The answer to the above question is Option 2) Left-outer Join
    A JOIN clause is used to combine rows from two or more tables, based on a related column between them.

    Here are the different types of the JOINs in SQL:

    1. (INNER) JOIN: Returns records that have matching values in both tables
    2. LEFT (OUTER) JOIN: Returns all records from the left table, and the matched records from the right table
    3. RIGHT (OUTER) JOIN: Returns all records from the right table, and the matched records from the left table
    4. FULL (OUTER) JOIN: Returns all records when there is a match in either left or right table

    We can see that left join keeps all the elements from the first relation irrespective of their presence in second relation.

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Similar Questions

  • 1.

    In RDBMS, which type of Join returns all rows that satisfy the join condition ?

  • filter_dramaExplanation
    Answer is : A

    Concept:

    Join operation is used to combine related tuples from two relations into single tuples. Join operation can be stated in terms of Cartesian product followed by SELECT operation.

    Join condition form: ANDAND……AND

    Explanation:

    There are various variations of join operations such as equi-join, natural join, theta join, inner join, outer join.

    • Natural join is performed by equating all attributes pairs that have the same name in the two relations.
    • Join operation with equality condition is known as equi-join.
    • Join operation which is used to combine data from multiple relations so that related information can be presented in a single table is known as inner join. Inner join is a type of match and merge operations defined as combination of Cartesian product and selection.
    • Outer join can be used when we want to keep all the tuples in the result of join regardless of whether or not they have matching tuples in other relation.
  • 2.

    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.

  • 3.

    Which of the following Relational Algebra operations can be used when you want to keep all the tuples of the first relation irrespective of whether or not they have matching tuples in the second relation?

  • filter_dramaExplanation
    Answer is : B

    The answer to the above question is Option 2) Left-outer Join
    A JOIN clause is used to combine rows from two or more tables, based on a related column between them.

    Here are the different types of the JOINs in SQL:

    1. (INNER) JOIN: Returns records that have matching values in both tables
    2. LEFT (OUTER) JOIN: Returns all records from the left table, and the matched records from the right table
    3. RIGHT (OUTER) JOIN: Returns all records from the right table, and the matched records from the left table
    4. FULL (OUTER) JOIN: Returns all records when there is a match in either left or right table

    We can see that left join keeps all the elements from the first relation irrespective of their presence in second relation.

  • 4.

    Which view that contains more than one table in the top-level FROM clause of the SELECT statement:

  • filter_dramaExplanation
    Answer is : C

    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.

  • 5.

    All ____ from multiple tables matching the join condition are returned by the inner join.

  • filter_dramaExplanation
    Answer is : A

    All rows from multiple tables matching the join condition are returned by the inner join.

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