SQL Joins MCQ
Joins MCQs : This section focuses on the "Joins" in the SQL. These Multiple Choice Questions (mcq) should be practiced to improve the SQL skills required for various interviews (campus interview, walk-in interview, company interview), placement, entrance exam and other competitive examinations.
1. A_____ is a query that retrieves rows from more than one table or view
A. Start
B. End
C. Join
D. All of the above
View Answer
Ans : C
Explanation: A Join is a query that retrieves rows from more than one table or view.
2. How many join types in join condition:
A. 2
B. 3
C. 4
D. 5
View Answer
Ans : D
Explanation: INNER JOIN, LEFT JOIN, RIGHT JOIN, FULL JOIN, EQUIJOIN.
3. Which are the join types in join condition:
A. Cross join
B. Natural join
C. Join with USING clause
D. All of the mentioned
View Answer
Ans : D
Explanation: INNER JOIN, LEFT JOIN, RIGHT JOIN, FULL JOIN, EQUIJOIN are the types of joins.
4. Which join refers to join records from the write 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. None of the above
View Answer
Ans : B
Explanation: Right outer join refers to join records from the write table that have no matching key in the left table are include in the result set.
5. Which view that contains more than one table in the top-level FROM clause of the SELECT statement:
A. Join view
B. Datable join view
C. Updatable join view
D. All of the mentioned
View Answer
Ans : C
Explanation: Updatable join view that contains more than one table in the top-level FROM clause of the SELECT statement.
6. Relation R1 has 10 tuples and 5 attributes. Relation R2 has 0 tuples and 7 attributes. When a CROSS JOIN is achieved between R1 and R2, how many tuples would the resultant set have?
A. 28
B. 10
C. 0
D. 35
View Answer
Ans : C
Explanation: When a CROSS JOIN is achieved between R1 and R2, 0 tuples the resultant set will have.
7. Which join is to be used between two tables A and B when the resultant table needs rows from A and B that matches the condition and rows from A that does not match the condition?
A. Outer Join
B. Cross Join
C. Inner Join
D. None of the above
View Answer
Ans : A
Explanation: Outer Join is to be used between two tables A and B when the resultant table needs rows from A and B that matches the condition and rows from A that does not match the condition.
8. Which of the following conditions has to be satisfied for INNER JOIN to work?
A. Columns used for joining must have same name
B. Columns used for joining can have same or different name
C. Columns used for joining must have different names
D. Columns used for joining must have different names
View Answer
Ans : B
Explanation: Columns used for joining can have same or different name is the following conditions has to be satisfied for INNER JOIN to work
9. Which of the following statement is TRUE about FULL OUTER JOIN created on two tables Table1 and Table2?
A. Retrieves all the unmatched rows of Table1
B. Retrieves all the unmatched rows of Table2
C. Retrieves both matched and unmatched rows of Table1 and Table2
D. Retrieves only matched rows of table1 and Table2
View Answer
Ans : C
Explanation: The statement is TRUE about FULL OUTER JOIN created on two tables Table1 and Table2 is Retrieves both matched and unmatched rows of Table1 and Table2.
10. Which join is equivalent to Cartesian Product?
A. INNER JOIN
B. OUTER JOIN
C. CROSS JOIN
D. NATURAL JOIN
View Answer
Ans : C
Explanation: CROSS JOIN is equivalent to Cartesian Product.
11. Which of the following statements are true?
A. INNER JOIN only retrieves those rows from Cartesian Product that satisfy the JOIN condition
B. FULL OUTER JOIN is same as CROSS JOIN
C. SELF JOIN is a special type of OUTER JOIN
D. Both A and C
View Answer
Ans : A
Explanation: INNER JOIN only retrieves those rows from Cartesian Product that satisfy the JOIN condition is true.
12. Which of the following statements are False?
A. RIGHT OUTER JOIN is equivalent to LEFT OUTER JOIN if order of tables are reversed
B. FULL OUTER JOIN is same as CROSS JOIN
C. SELF JOIN is a special type of OUTER JOIN
D. Both B and C
View Answer
Ans : D
Explanation: Both B and C option are False statements.
13. To specify a normal join, using the keyword inner is?
A. Mandatory
B. Optional
C. Independent
D. Free
View Answer
Ans : B
Explanation: To specify a normal join, using the keyword inner is Optional.
14. Left outer join preserves tuples only in the relation named before
A. Right outer join operation
B. Right inner join operation
C. Left inner join operation
D. Left outer join operation
View Answer
Ans : D
Explanation: Left outer join preserves tuples only in the relation named before Left outer join operation.
15. The following SQL is which type of join?
A. Equi-join
B. Natural join
C. Outer join
D. Cartesian join
View Answer
Ans : A
Explanation: Equi-join joins only same data entry field. For example, one table contains department id and another table should contain department id.
16. The following SQL is which type of join?
A. Equi-join
B. Natural join
C. Outer join
D. Cartesian join
View Answer
Ans : D
Explanation: Cartesian Join is simply the joining of one or more table which returns the product of all the rows in these tables.
17. Evaluate this SQL statement: In the statement, which capabilities of a SELECT statement are performed?
A. Selection, projection, join
B. Difference, projection, join
C. Selection, intersection, join
D. Intersection, projection, join
View Answer
Ans : A
Explanation: In the statement, Selection, projection, join capabilities of a SELECT statement are performed
18. A SELECT statement can be used to perform these three functions:
- Choose rows from a table.
- Choose columns from a table.
- Bring together data that is stored in different tables by creating a link between them.
Which set of keywords describes these capabilities?
A. difference, projection, join
B. selection, projection, join
C. Selection, intersection, join
D. Intersection, projection, join
View Answer
Ans : B
Explanation: selection, projection, join is the answer.
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