Chapter Exam

Chapter-4 Querying and SQL Functions — Online MCQ Test

Q: Which SQL function is used to count the number of rows in a table?

Answer: B. COUNT() — COUNT() is the aggregate function specifically designed to count the number of rows that match a specified condition in a table.

Q: What does the AVG() function return?

Answer: B. The average or mean value of a numeric column — AVG() calculates and returns the average (mean) of all numeric values in a specified column.

Q: Which of the following is NOT an aggregate function?

Answer: C. ROUND() — ROUND() is a scalar/single-row function that rounds numeric values, not an aggregate function that operates on multiple rows.

INFORMATICS PRACTICES · Grade 12 · CBSE(NCERT)

Practice Chapter-4 Querying and SQL Functions with a free chapter-wise online MCQ test for CBSE(NCERT) Grade 12 INFORMATICS PRACTICES. This chapter covers: SQL - single row functions - aggregate functions - SUM - AVG - COUNT - MAX - MIN - GROUP BY - HAVING - ORDER BY - table joins. AI-generated questions from basic to board-exam level, with instant results and explanations.

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Chapter-4 Querying and SQL Functions — Important Questions & Answers (FAQ)

Frequently asked questions from CBSE(NCERT) Grade 12 INFORMATICS PRACTICES — Chapter-4 Querying and SQL Functions, with answers and explanations. These are sample questions; the exam has its own separate question set.

Which SQL function is used to count the number of rows in a table?

A. SUM()
B. COUNT() ✓
C. AVG()
D. MAX()

Answer: B. COUNT()
COUNT() is the aggregate function specifically designed to count the number of rows that match a specified condition in a table.

What does the AVG() function return?

A. The total sum of all values
B. The average or mean value of a numeric column ✓
C. The highest value in a column
D. The lowest value in a column

Answer: B. The average or mean value of a numeric column
AVG() calculates and returns the average (mean) of all numeric values in a specified column.

Which of the following is NOT an aggregate function?

A. SUM()
B. COUNT()
C. ROUND() ✓
D. AVG()

Answer: C. ROUND()
ROUND() is a scalar/single-row function that rounds numeric values, not an aggregate function that operates on multiple rows.

What is a single-row function in SQL?

A. A function that works on multiple rows at once
B. A function that processes each row independently and returns one result per input row ✓
C. A function used only with GROUP BY
D. A function that can only be used in WHERE clause

Answer: B. A function that processes each row independently and returns one result per input row
Single-row functions operate on each row individually and return one result for each input row, unlike aggregate functions that work on multiple rows.

Consider this scenario: You need to find the department with the highest total salary expense. Which query structure is most appropriate?

A. SELECT Department FROM Employees ORDER BY Salary DESC LIMIT 1
B. SELECT Department, SUM(Salary) FROM Employees GROUP BY Department ORDER BY SUM(Salary) DESC LIMIT 1 ✓
C. SELECT Department, MAX(Salary) FROM Employees GROUP BY Department
D. SELECT Department FROM Employees WHERE Salary = MAX(Salary)

Answer: B. SELECT Department, SUM(Salary) FROM Employees GROUP BY Department ORDER BY SUM(Salary) DESC LIMIT 1
This query correctly groups by department, sums all salaries per department, orders by total salary descending, and limits to the top result.