30 Important SQL Queries for CBSE Class 12 Board Exam 2026-27

SQL carries 8 marks in the CBSE Class 12 Computer Science board exam. Every year, 2-3 questions come directly from SQL. This post covers 30 queries you must practice before your exam.

We will use these two tables throughout:

Table: STUDENT

RollNo	Name	Class	Marks	City
1	Aman	12A	85	Delhi
2	Priya	12B	92	Mumbai
3	Rahul	12A	67	Delhi
4	Sneha	12B	78	Kolkata
5	Vikram	12A	91	Chennai
6	Kavita	12B	54	Mumbai
7	Arjun	12A	73	Delhi
8	Meera	12B	88	Chennai

Table: TEACHER

TID	TName	Subject	Salary	Department
101	Mr Sharma	Physics	55000	Science
102	Ms Gupta	Chemistry	48000	Science
103	Mr Verma	English	42000	Humanities
104	Ms Jain	Maths	60000	Science
105	Mr Roy	History	38000	Humanities

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Part 1: Basic SELECT Queries

Query 1: Select All Records

SELECT * FROM STUDENT;

This displays every row and column from the STUDENT table.

Query 2: Select Specific Columns

SELECT Name, Marks FROM STUDENT;

Name    | Marks
--------|------
Aman    | 85
Priya   | 92
Rahul   | 67
Sneha   | 78
Vikram  | 91
Kavita  | 54
Arjun   | 73
Meera   | 88

Query 3: DISTINCT, Remove Duplicates

SELECT DISTINCT City FROM STUDENT;

City
--------
Delhi
Mumbai
Kolkata
Chennai

Query 4: WHERE Clause

SELECT Name, Marks FROM STUDENT WHERE Marks > 80;

Name   | Marks
-------|------
Aman   | 85
Priya  | 92
Vikram | 91
Meera  | 88

Query 5: AND / OR

SELECT * FROM STUDENT WHERE City = 'Delhi' AND Marks > 70;

RollNo | Name  | Class | Marks | City
-------|-------|-------|-------|------
1      | Aman  | 12A   | 85    | Delhi
7      | Arjun | 12A   | 73    | Delhi

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Part 2: Operators, BETWEEN, IN, LIKE

Query 6: BETWEEN

SELECT Name, Marks FROM STUDENT WHERE Marks BETWEEN 70 AND 90;

Name  | Marks
------|------
Aman  | 85
Sneha | 78
Arjun | 73
Meera | 88

Note: BETWEEN is inclusive, it includes both 70 and 90.

Query 7: IN

SELECT * FROM STUDENT WHERE City IN ('Delhi', 'Mumbai');

This returns all students from Delhi or Mumbai. It is a shorter way to write multiple OR conditions.

Query 8: NOT IN

SELECT Name, City FROM STUDENT WHERE City NOT IN ('Delhi');

Returns students from all cities except Delhi.

Query 9: LIKE with % Wildcard

SELECT Name FROM STUDENT WHERE Name LIKE 'A%';

Name
-----
Aman
Arjun

% matches zero or more characters. A% means names starting with 'A'.

Query 10: LIKE with _ Wildcard

SELECT Name FROM STUDENT WHERE Name LIKE '____a';

Name
------
Priya
Sneha
Meera

Each _ matches exactly one character. Five characters total, ending with 'a'.

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Part 3: ORDER BY

Query 11: Sort Ascending

SELECT Name, Marks FROM STUDENT ORDER BY Marks;

Name   | Marks
-------|------
Kavita | 54
Rahul  | 67
Arjun  | 73
Sneha  | 78
Aman   | 85
Meera  | 88
Vikram | 91
Priya  | 92

Query 12: Sort Descending

SELECT Name, Marks FROM STUDENT ORDER BY Marks DESC;

Returns students sorted from highest to lowest marks.

Query 13: ORDER BY Multiple Columns

SELECT * FROM STUDENT ORDER BY City ASC, Marks DESC;

First sorts by City alphabetically, then by Marks in descending order within each city.

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Part 4: Aggregate Functions

These are asked almost every year. Memorize all five: COUNT, SUM, AVG, MAX, MIN.

Query 14: COUNT

SELECT COUNT(*) FROM STUDENT;

COUNT(*)
--------
8

Query 15: SUM

SELECT SUM(Marks) FROM STUDENT;

SUM(Marks)
----------
628

Query 16: AVG

SELECT AVG(Marks) FROM STUDENT;

AVG(Marks)
----------
78.5

Query 17: MAX and MIN

SELECT MAX(Marks), MIN(Marks) FROM STUDENT;

MAX(Marks) | MIN(Marks)
-----------|----------
92         | 54

Query 18: COUNT with Condition

SELECT COUNT(*) FROM STUDENT WHERE City = 'Delhi';

COUNT(*)
--------
3

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Part 5: GROUP BY and HAVING

Query 19: GROUP BY

SELECT City, COUNT(*) FROM STUDENT GROUP BY City;

City    | COUNT(*)
--------|--------
Delhi   | 3
Mumbai  | 2
Kolkata | 1
Chennai | 2

Query 20: GROUP BY with Aggregate

SELECT City, AVG(Marks) FROM STUDENT GROUP BY City;

City    | AVG(Marks)
--------|----------
Delhi   | 75.00
Mumbai  | 73.00
Kolkata | 78.00
Chennai | 89.50

Query 21: HAVING Clause

SELECT City, COUNT(*) FROM STUDENT GROUP BY City HAVING COUNT(*) > 1;

City    | COUNT(*)
--------|--------
Delhi   | 3
Mumbai  | 2
Chennai | 2

Important: HAVING is used to filter groups (after GROUP BY). WHERE is used to filter rows (before GROUP BY). This distinction is a favourite board exam question.

Query 22: GROUP BY with HAVING and WHERE

SELECT Class, AVG(Marks) FROM STUDENT WHERE City != 'Kolkata' GROUP BY Class HAVING AVG(Marks) > 75;

This first filters out Kolkata students (WHERE), groups by Class (GROUP BY), and then keeps only groups with average marks above 75 (HAVING).

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Part 6: NULL Handling

Query 23: IS NULL

SELECT Name FROM STUDENT WHERE Marks IS NULL;

Use IS NULL, never = NULL. This is a common mistake in exams.

Query 24: IS NOT NULL

SELECT Name FROM STUDENT WHERE Marks IS NOT NULL;

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Part 7: DDL and DML Commands

Query 25: CREATE TABLE

CREATE TABLE STUDENT (
    RollNo INT PRIMARY KEY,
    Name VARCHAR(50) NOT NULL,
    Marks INT,
    City VARCHAR(30) DEFAULT 'Delhi'
);

Query 26: INSERT INTO

INSERT INTO STUDENT VALUES (9, 'Riya', '12A', 82, 'Pune');

Or insert into specific columns:

INSERT INTO STUDENT (RollNo, Name, Class) VALUES (10, 'Karan', '12B');

Query 27: UPDATE

UPDATE STUDENT SET Marks = 90 WHERE RollNo = 3;

Always use WHERE with UPDATE, or it changes every row.

Query 28: DELETE

DELETE FROM STUDENT WHERE Marks < 60;

This removes Kavita (Marks = 54) from the table.

Query 29: ALTER TABLE, Add Column

ALTER TABLE STUDENT ADD Grade CHAR(2);

Query 30: ALTER TABLE, Drop Column

ALTER TABLE STUDENT DROP COLUMN Grade;

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Board Exam Pattern Tips

1. SQL questions carry 2-3 marks each. Write the complete query, not just fragments.
2. Write table output neatly. Draw proper column headers when the question says "write the output."
3. GROUP BY + HAVING is a guaranteed question. Know the difference between WHERE and HAVING.
4. Aggregate functions ignore NULL values. COUNT(*) counts all rows, but COUNT(column) skips NULLs.
5. ORDER BY default is ASC. You do not need to write ASC explicitly.
6. String values need single quotes - WHERE Name = 'Aman', not double quotes.
7. Practice writing output tables. The examiner checks if you draw the correct rows AND correct columns.

Quick Reference: SQL Clause Order

Always write SQL clauses in this order:

SELECT column(s)
FROM table
WHERE condition
GROUP BY column
HAVING condition
ORDER BY column;

Remember the order: S-F-W-G-H-O ("Some Friends Work on Group Homework Online").

Master these 30 queries and you will confidently handle any SQL question in the CBSE Class 12 board exam. Practice writing them by hand, that is how the exam works.