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SQL Multiple Choice Questions – MCQ3

Answers

1) d) We can insert and delete rows in a view

2) d) Order By

Order By clause is used to sort the retrieved data in ascending or descending order. Group By clause is used to group the result-set by one or more columns. Order and Group are not valid SQL commands.

3) a) True

NULL signifies an unknown value or a value which doesn’t exist during the creation of the record.

4) c) Drop

5) a) <>

6) c) Select top

7) d) Limit

All database systems does not supports SELECT TOP clause. It can be used in SQL. Mysql supports the LIMIT clause to fetch a limited number of records from the database table.

8) d) All correct

9) b) Selects a record if both conditions are true

10) b) Adds a value to a column’s existing value

11) a) True

12) d) No syntax error

13) d) No error

14) a) XOR operator

SQL does not have an XOR logical operator. Use AND/OR instead.

15) d) All Correct

The compound operator ‘*=’ is correctly used to double the salary of specified employees.

16) a) It functions as a WHERE clause

Without GROUP BY, HAVING functions like a WHERE clause, filtering rows based on specified conditions.

17) a) The query fails

Using a column in SELECT that is not part of GROUP BY without an aggregate function causes the query to fail.

18) c) GROUP BY Salary

GROUP BY should be used with the column mentioned in SELECT, here it should be GROUP BY Department.

19) d) HAVING AverageSalary > 50000

HAVING should be used with an aggregate function directly, not with an alias.

20) a) SELECT Name

Name should be included in the GROUP BY clause or used within an aggregate function.

21) d) No Error

The query correctly groups by Department and uses HAVING to filter groups.

22) d) All Correct

ORDER BY 3 is correct, indicating ordering by the third column in the SELECT list.

23) c) WHERE MAX(Salary) > 50000

Aggregate functions such as MAX should be used in the HAVING clause when filtering groups created by the GROUP BY clause.

24) c) No error

The query correctly uses HAVING with ALL to compare counts across departments.

25) c) HAVING clause misuse

The original statement had an error in the HAVING clause. It incorrectly used the alias ‘TotalEmployees’. The correct HAVING clause should be “HAVING COUNT(*) > 5”.

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Welcome to the SQL Quiz!

SQL Multiple Choice Questions – MCQ1

Answers

1) a) Structured Query Language

2) a) CREATE TABLE

CREATE TABLE Students (ID int PRIMARY KEY, Name varchar(50));

3) a) SELECT

SELECT column1, column2, ... FROM table_name;

4) a) Primary Key

5) c) Reduce data redundancy

6) c) Relational

7) a) Deletes a table called Student

8) a) UPDATE

UPDATE table_name
SET column1 = value1, column2 = value2, ...
WHERE condition;

9) a) INSERT INTO

INSERT INTO table_name (column1, column2, column3, ...)
VALUES (value1, value2, value3, ...);

10) a) DELETE

DELETE FROM table_name WHERE condition;

11) a) Select, From

12) d) ;

13) b) ALTER

ALTER TABLE table_name
ADD column_name datatype;

14) a) DROP deletes the table, TRUNCATE deletes only the table data

15) a) TABEL

16)

a) SELECT FirstName FROM Students

17)

a) SELECT * FROM Students

18)

a) SELECT * FROM Students WHERE FirstName='Peter'

19)

a) SELECT * FROM Students WHERE FirstName LIKE 'a%'

20) c) By ensuring all operations within the transaction are completed before committing

21) a) PRIMARY

It should be PRIMARY KEY instead of PRIMARY.

CREATE TABLE Students (ID int PRIMARY KEY, Name varchar(50));

22) d) All Correct

23) b) Modifies an existing record

24) c) Specifies which records to delete

25) a) All Correct