Supabase Backend as a Service · Lesson

Creating Tables and Columns

Hands-on experience creating new tables, defining column types, setting primary keys, and adding foreign key constraints directly in Supabase.

Creating Tables and Columns is a free Supabase Backend as a Service lesson on CoddyKit — lesson 2 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Supabase Backend as a Service learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.

Building Blocks of Your Data

Welcome to creating your first database! Just like organizing information in a spreadsheet, databases use tables to hold related data.

Think of a table as a single sheet in your spreadsheet. Each table has columns, which are like the headings, defining what kind of information each entry will hold.

Into the Supabase Studio

Supabase provides a powerful web interface called the Supabase Studio (or Dashboard) to manage your project. This is where we'll create our tables.

First, log in to your Supabase project.
On the left sidebar, click the Database icon (it looks like a cylinder).
Then, select Table Editor from the submenu.

Your First Table

Once in the Table Editor, you'll see an option to create a new table. Let's make one for 'products'.

Click the '+ New Table' button.
Give your table a descriptive name, like products.
Keep the schema as public for now. This is the default container for your tables.
Click 'Save' to create the empty table.

Adding Columns to Your Table

An empty table isn't very useful! Now, let's add some columns to our products table. Columns define the specific pieces of information each product will have.

In the table editor, find your new products table.
Click '+ Add column'.
You'll specify the column's name, data type, and other properties.

Choosing the Right Data Type

Each column needs a data type, which tells the database what kind of data it can store (text, numbers, dates, etc.).

text: For names, descriptions, or any string of characters.
integer: For whole numbers (e.g., quantity).
numeric or decimal: For numbers with decimal points (e.g., price).
boolean: For true/false values (e.g., is_available).
uuid: A universally unique identifier, great for primary keys.

Unique Identifiers: Primary Keys

Every table needs a Primary Key (PK). This is a special column (or set of columns) that uniquely identifies each row in the table. No two rows can have the same primary key value.

A common practice is to use a uuid (Universally Unique Identifier) as the primary key. Supabase can automatically generate these for you.

When adding an id column, set its type to uuid.
Check the 'Is Primary Key' box.
Set the 'Default Value' to gen_random_uuid(). This will auto-generate a unique ID for every new row.

Connecting Your Data: Foreign Keys

Databases are powerful because they can link related information across different tables. This is done using a Foreign Key (FK).

A foreign key in one table points to the primary key of another table. It establishes a relationship, ensuring data consistency. For example, a posts table might have a user_id foreign key linking to the id in the users table.

Practical Example: Users & Posts

Let's create two tables, users and posts, and link them using a foreign key. Run this SQL directly in the Supabase SQL Editor (accessible from the left sidebar).

CREATE TABLE users (
  id uuid DEFAULT gen_random_uuid() PRIMARY KEY,
  username text NOT NULL UNIQUE,
  email text NOT NULL UNIQUE
);

CREATE TABLE posts (
  id uuid DEFAULT gen_random_uuid() PRIMARY KEY,
  user_id uuid REFERENCES users(id) ON DELETE CASCADE,
  title text NOT NULL,
  content text,
  created_at timestamp WITH TIME ZONE DEFAULT now()
);

Reviewing Your Database Structure

After running the SQL or creating tables via the UI, you can always review your database structure in the Supabase Studio.

Go back to the Table Editor.
You'll see your new tables listed.
Click on a table name to see its columns, data types, and any primary or foreign key constraints.
The 'Relationships' tab can also show how your tables are connected.

Test Your Knowledge

Which of the following statements about database tables and keys are TRUE?

Tables & Columns: Recap

Great job! In this lesson, you've learned the fundamental concepts of database structure:

Tables are containers for related data.
Columns define the specific attributes within a table.
Data types specify the kind of data a column can hold.
Primary Keys uniquely identify each row.
Foreign Keys link tables together, defining relationships.

You now have the skills to start structuring your Supabase database effectively. Next, we'll learn how to put data into these tables!

Frequently asked questions

Is the “Creating Tables and Columns” lesson free?

Yes — the full text of “Creating Tables and Columns” is free to read here on the web, and the Supabase Backend as a Service course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Supabase Backend as a Service course, upgrade to CoddyKit PRO.

What will I learn in “Creating Tables and Columns”?

Hands-on experience creating new tables, defining column types, setting primary keys, and adding foreign key constraints directly in Supabase. You practise Supabase Backend as a Service with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.

Do I need any experience to start Supabase Backend as a Service?

No prior experience is required. Supabase Backend as a Service on CoddyKit is structured for beginners through advanced learners; this is — lesson 2 of 4, so you can start here or from the beginning and move at your own pace.

How long does the “Creating Tables and Columns” lesson take?

Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.

Can I write and run code in this Supabase Backend as a Service lesson?

Yes. Every Supabase Backend as a Service lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.

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