Every database is made up of tables, and understanding how they work is the key to mastering SQL.

In this episode, you’ll learn:

• What a table is in SQL
• The difference between rows and columns
• What data types and primary keys are
  Let’s dive in!

 What is a Table in SQL?

A table in SQL is like a spreadsheet that holds related data. It’s made of:

• Columns (fields or attributes)
• Rows (records or entries)

Simple Definition:

A table stores data in a structured format using rows and columns, where each row is a record and each column holds specific information.

 Table Structure Example

Here’s a basic SQL table for storing student data:

Table: students

id	name	course	marks
1	Ayesha	Math	85
2	Ali	Physics	78
3	Zara	English	90

• Each row represents one student
• Each column holds one type of information (e.g., name, marks)

 Rows vs Columns

Element	Description
Row	A single record (e.g., data of one student)
Column	A specific attribute (e.g., course, marks)

Columns define the structure of the table, while rows hold the actual data.

 What is a Primary Key?

A Primary Key is a column (or set of columns) that uniquely identifies each row in a table.

In our example:

id INT PRIMARY KEY

The id column is the primary key—it ensures that no two students have the same ID.

Primary keys help:

• Avoid duplicate records
• Improve search speed
• Connect tables through relationships

 Common Data Types in SQL Tables

Each column must have a data type—this defines what kind of data can be stored.

Data Type	Used For	Example Values
INT	Whole numbers	1, 50, 999
VARCHAR(n)	Text (n = max characters)	‘Ali’, ‘Physics’
DATE	Calendar dates	‘2025-06-30’
FLOAT	Decimal numbers	85.5, 3.14
BOOLEAN	True/False values	TRUE, FALSE

Example:

CREATE TABLE students (

id INT PRIMARY KEY,

name VARCHAR(50),

course VARCHAR(50),

marks INT

);

This creates a table with 4 columns and specifies the data type of each.

 Summary

• Tables store data in rows and columns
• Rows = individual records
• Columns = fields/attributes
• Primary keys uniquely identify each row
• Data types define what kind of info each column can hold

Related:

• Basic SQL Commands | SELECT, INSERT, UPDATE, DELETE
• SQL Basics for Beginners | What is SQL and How It Works