SQL Quiz

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

• MAX()

• COUNT()

• SUM()

• AVG()

The SQL function SUM() is used to:

• Find the largest value in a column

• Calculate the total of numeric values in a column

• Count the number of rows

• Return the average value

Which query will calculate the total Amount of delivered orders?

• SELECT SUM(Amount) FROM Orders WHERE Status = 'Delivered';

• SELECT COUNT(Amount) FROM Orders WHERE Status = 'Delivered';

• SELECT AVG(Amount) FROM Orders WHERE Status = 'Delivered';

• SELECT MAX(Amount) FROM Orders WHERE Status = 'Delivered';

Assertion (A): The COUNT(*) function counts all rows in a table, including rows with NULL values. Reason (R): COUNT(*) is designed to provide a total count of rows, irrespective of column values.

• Both A and R are true, and R is the correct explanation of A.

• Both A and R are true, but R is not the correct explanation of A.

• A is true, but R is false.

• A is false, but R is true.

The GROUP BY clause can be used without aggregate functions.

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OFF

A student table has columns RollNo, Name, Marks. Write a query to find the average marks of all students.

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Justify the purpose of the HAVING clause in SQL.

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The query SELECT MAX(Marks) FROM student; will:

• Return the name of the student with the highest marks

• Return the maximum marks from the Marks column

• Return the total marks

• Return the number of students

What is the result of SELECT Category, SUM(Price) FROM Sales GROUP BY Category;?

• A: 250, B: 200

• A: 100, B: 200

• A: 250, B: 150

• Error

Assertion (A): ORDER BY sorts the result set. Reason (R): ORDER BY can only be applied to numeric columns.

• Both A and R are true, and R is the correct explanation of A.

• Both A and R are true, but R is not the correct explanation of A.

• A is true, but R is false.

• A is false, but R is true.