MySQL Mastery Hub - Complete Learning Platform for CBSE Class 12

What is MySQL?

Fundamental

MySQL is a Relational Database Management System (RDBMS) that uses Structured Query Language (SQL). It's:

Open Source - Free to use and modify
Relational - Data stored in tables with relationships
Client-Server - Uses client-server architecture
ACID Compliant - Ensures data integrity

Key Components

1. Database: Container for tables (SCHOOL)
2. Table: Collection of rows and columns (STUDENT)
3. Column/Field: Single data item (Name, Marks)
4. Row/Record: Complete set of related data (Amit's details)

Quick Quiz

Which SQL command is used to create a new database?

CREATE DATABASE

MAKE DATABASE

NEW DATABASE

ADD DATABASE

Table Creation Syntax

Important

Basic syntax for creating tables:

Syntax

CREATE TABLE table_name (
    column1 datatype constraints,
    column2 datatype constraints,
    column3 datatype constraints,
    ...
    PRIMARY KEY (one_or_more_columns)
);

Common Constraints

NOT NULL - Column cannot have NULL values
UNIQUE - All values must be different
PRIMARY KEY - Unique identifier for each row
FOREIGN KEY - Links to another table's PRIMARY KEY
DEFAULT - Sets default value for column
AUTO_INCREMENT - Automatically increases value

SELECT Statement - Complete Guide

Core Concept

The SELECT statement retrieves data from a database. Basic syntax:

SELECT Syntax

-- Select all columns
SELECT * FROM table_name;

-- Select specific columns
SELECT column1, column2 FROM table_name;

-- Select with condition
SELECT * FROM table_name
WHERE condition;

-- Select with sorting
SELECT * FROM table_name
ORDER BY column_name ASC|DESC;

Practice Exercise

Write a query to select names of all students from Class 12, sorted alphabetically:

WHERE Clause Operators

Must Know

Complete list of operators used in WHERE clause:

Operator	Description	Example
=	Equal	Marks = 85
!= or <>	Not equal	Class != 12
>	Greater than	Marks > 80
<	Less than	Marks < 33
>=	Greater than or equal	Marks >= 90
<=	Less than or equal	Class <= 12
BETWEEN	Between a range	Marks BETWEEN 70 AND 90
LIKE	Pattern matching	Name LIKE 'A%'
IN	Matches any value in list	Class IN (11, 12)
IS NULL	NULL value check	Email IS NULL

Aggregate Functions - Complete Reference

Exam Focus

Aggregate functions perform calculations on multiple rows and return a single value:

COUNT()

Returns number of rows

SELECT COUNT(*) FROM students;

COUNT(*) counts all rows
COUNT(column) counts non-NULL values
Use with GROUP BY for grouped counts

SUM()

Returns total sum of numeric column

SELECT SUM(Marks) FROM students;

Works only on numeric columns
Ignores NULL values
Use with WHERE to filter before sum

AVG()

Returns average value

SELECT AVG(Marks) FROM students;

Ignores NULL values
Returns decimal (use ROUND())
Works on numeric columns only

MAX()

Returns maximum value

SELECT MAX(Marks) FROM students;

Works on numbers, dates, strings
For strings: alphabetical order
Ignores NULL values

MIN()

Returns minimum value

SELECT MIN(Marks) FROM students;

Opposite of MAX()
Works on various data types
Often used with GROUP BY

MySQL Data Types - Complete Reference

Essential Knowledge

Choosing the right data type is crucial for database efficiency and integrity:

Numeric Types

INT - Whole numbers (-2^31 to 2^31-1)
TINYINT - Very small integers (-128 to 127)
BIGINT - Large integers
DECIMAL(p,s) - Exact decimal numbers
FLOAT - Approximate floating-point

String Types

VARCHAR(n) - Variable length string (1-65535)
CHAR(n) - Fixed length string (1-255)
TEXT - Large text (up to 65KB)
LONGTEXT - Very large text (up to 4GB)

Date & Time

DATE - YYYY-MM-DD format
DATETIME - YYYY-MM-DD HH:MM:SS
TIMESTAMP - Unix timestamp
TIME - HH:MM:SS format
YEAR - Year value (1901-2155)

Other Types

BOOLEAN - TRUE/FALSE values
ENUM - List of allowed values
SET - Multiple values from list
BLOB - Binary large objects

Best Practices

1. Use INT for IDs and counts
2. Use VARCHAR for variable length strings (names, addresses)
3. Use CHAR for fixed length codes (country codes, gender)
4. Use DECIMAL for exact monetary values
5. Use smallest data type that fits your data

MySQL Quick Reference Cheat Sheet

Print & Save

DDL Commands

Data Definition Language

CREATE DATABASE - Create new database
CREATE TABLE - Create new table
ALTER TABLE - Modify table structure
DROP TABLE - Delete table
TRUNCATE TABLE - Delete all rows

DML Commands

Data Manipulation Language

INSERT INTO - Add new rows
UPDATE - Modify existing rows
DELETE FROM - Remove rows
SELECT - Retrieve data

Clause Reference

Order of execution:

FROM - Tables
WHERE - Filter rows
GROUP BY - Group rows
HAVING - Filter groups
SELECT - Select columns
ORDER BY - Sort results

Common Patterns

Frequently used queries:

SELECT * FROM table LIMIT 10;
SELECT DISTINCT column FROM table;
SELECT COUNT(*) FROM table WHERE condition;
UPDATE table SET col=val WHERE condition;

Download Cheat Sheet

Click below to download a printable PDF version of this cheat sheet:

Practice Exercises with Solutions

Hands-on Learning

Exercise 1: Table Creation

Create a table EMPLOYEE with columns: EmpID (INT, Primary Key), Name (VARCHAR(50)), Department (VARCHAR(30)), Salary (DECIMAL(10,2)), JoinDate (DATE).

Exercise 2: Complex Query

Given a table ORDERS with columns: OrderID, CustomerID, OrderDate, Amount. Write a query to find customers who have placed more than 5 orders.

Exercise 3: UPDATE with JOIN

You have two tables: STUDENTS (StudentID, Name, TotalMarks) and GRADES (StudentID, Grade). Write a query to update the Grade to 'A' for all students with TotalMarks > 90.

CBSE MySQL Mock Test

1 Which SQL statement is used to extract data from a database?

SELECT

EXTRACT

GET

OPEN

2 Which operator is used to search for a specified pattern in a column?

MATCH

FIND

3 Which SQL keyword is used to sort the result-set?

ORDER BY

SORT

SORT BY

ARRANGE BY

4 Which function returns the largest value of the selected column?

MAX()

LARGEST()

BIG()

TOP()

5 What does the PRIMARY KEY constraint do?

Uniquely identifies each record

Speeds up queries

Prevents NULL values

Creates backup of data

Advanced MySQL Concepts

For High Scorers

Advanced topics covered in our complete course:

Joins (INNER, LEFT, RIGHT, FULL)
Subqueries (Nested queries)
Views (Virtual tables)
Indexes (Performance optimization)
Stored Procedures
Triggers (Automatic actions)
Transactions (ACID properties)
Normalization (1NF, 2NF, 3NF)
Backup and Recovery
User Management & Permissions

Pro Tip

For CBSE Class 12, focus on mastering Joins, Subqueries, and Views. These are most frequently asked in board exams. Practice at least 10 different problems for each concept.

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Learning Stats

Topics Completed: 5/20

Exercises Solved: 0/15

Mock Test Score: Not taken

What is MySQL?

Key Components

Quick Quiz

Table Creation Syntax

Common Constraints

SELECT Statement - Complete Guide

Practice Exercise

WHERE Clause Operators

Aggregate Functions - Complete Reference

COUNT()

SUM()

AVG()

MAX()

MIN()

MySQL Data Types - Complete Reference

Numeric Types

String Types

Date & Time

Other Types

Best Practices

MySQL Quick Reference Cheat Sheet

DDL Commands

DML Commands

Clause Reference

Common Patterns

Download Cheat Sheet

Practice Exercises with Solutions

Exercise 1: Table Creation

Exercise 2: Complex Query

Exercise 3: UPDATE with JOIN

CBSE MySQL Mock Test

1 Which SQL statement is used to extract data from a database?

2 Which operator is used to search for a specified pattern in a column?

3 Which SQL keyword is used to sort the result-set?

4 Which function returns the largest value of the selected column?

5 What does the PRIMARY KEY constraint do?

Advanced MySQL Concepts

Pro Tip

Quick Navigation

Learning Stats

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