Database Questions and Answers – Join Expressions

This set of Database Multiple Choice Questions & Answers (MCQs) focuses on “Join Expressions”.

1. The____condition allows a general predicate over the relations being joined.
a) On
b) Using
c) Set
d) Where
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2. Which of the join operations do not preserve non matched tuples?
a) Left outer join
b) Right outer join
c) Inner join
d) Natural join
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3.

SELECT *
  FROM student JOIN takes USING (ID);

The above query is equivalent to
a)

   SELECT *
   FROM student INNER JOIN takes USING (ID);

b)

   SELECT *
   FROM student OUTER JOIN takes USING (ID);

c)

   SELECT *
   FROM student LEFT OUTER JOIN takes USING (ID);

d) None of the mentioned
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4. What type of join is needed when you wish to include rows that do not have matching values?
a) Equi-join
b) Natural join
c) Outer join
d) All of the mentioned
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5. How many tables may be included with a join?
a) One
b) Two
c) Three
d) All of the mentioned
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6. Which are the join types in join condition:
a) Cross join
b) Natural join
c) Join with USING clause
d) All of the mentioned
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7. How many join types in join condition:
a) 2
b) 3
c) 4
d) 5
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8. Which join refers to join records from the right table that have no matching key in the left table are include in the result set:
a) Left outer join
b) Right outer join
c) Full outer join
d) Half outer join
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9. The operation which is not considered a basic operation of relational algebra is
a) Join
b) Selection
c) Union
d) Cross product
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10. In SQL the statement select * from R, S is equivalent to
a) Select * from R natural join S
b) Select * from R cross join S
c) Select * from R union join S
d) Select * from R inner join S
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Sanfoundry Global Education & Learning Series – Database Management System.