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wip <!-- This is an auto-generated comment: release notes by coderabbit.ai --> ## Summary by CodeRabbit # Release Notes * **New Features** * Added a new Learn application offering foundational Supabase courses with interactive documentation * Courses include Architecture, Authentication, Data Fundamentals, Security, Storage, Realtime, and Edge Functions * Chapter tracking and progress indicators for course completions * Responsive sidebar navigation with search/command menu * Theme switching support (light, dark, classic dark modes) * Mobile-friendly course interface <!-- end of auto-generated comment: release notes by coderabbit.ai --> --------- Co-authored-by: Alan Daniel <stylesshjs@gmail.com> Co-authored-by: Claude Sonnet 4.5 <noreply@anthropic.com>
145 lines
4.2 KiB
Plaintext
145 lines
4.2 KiB
Plaintext
---
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title: Data Fundamentals
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description: 'Learn how data is structured in Postgres: tables, rows, columns, and keys.'
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chapterNumber: 2
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explore:
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- title: Supabase Docs
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link: https://supabase.com/docs/guides/database/overview
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itemType: doc
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- title: Postgres for Beginners
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link: https://www.postgresqltutorial.com/
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itemType: reference
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---
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Before we store any information in Supabase, we need to understand how data is
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organized in Postgres. Supabase uses Postgres as its database, which means data
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is arranged in a structured and predictable way. This helps keep your app
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organized, consistent, and easy to query.
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The core ideas are simple: you create tables to hold related data, and each
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table has rows (records) and columns (fields). Once you understand that pattern,
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you can model almost anything.
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---
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## Tables, rows, and columns
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A table is like a spreadsheet. It has:
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- **Columns**: the fields that define what kind of data the table stores
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- **Rows**: the individual entries in the table
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Imagine a table for storing notes:
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```text
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| id | content | created_at |
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|----|------------------|----------------------|
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| 1 | Buy groceries | 2025-01-10 14:22:11 |
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| 2 | Call the dentist | 2025-01-10 15:08:54 |
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```
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- Each **row** is a single note.
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- Each **column** represents one piece of information about the note.
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---
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## Data types
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Every column has a data type. This describes the kind of value that can be
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stored there.
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Some common data types:
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```text
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| Data type | Example value | Meaning |
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| ----------- | ---------------- | ----------------------------- |
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| text | Hello world | A string of characters |
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| integer | 42 | A number without decimals |
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| boolean | true | Yes/no or on/off values |
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| timestamptz | 2025-01-10 14:22 | Date and time (with timezone) |
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| json | {"name": "John"} | A JSON object |
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```
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Choosing correct types makes your data easier to work with and protects you from
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unexpected values.
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---
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## Primary keys
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Most tables include a primary key. This is a column that uniquely identifies each
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row. In many Supabase projects, this column is named `id` and uses a type called
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`uuid`, which automatically generates a unique value.
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You create this column in the table definition like this:
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```text
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id uuid primary key default gen_random_uuid()
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```
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You generally don't need to think about it after setting it up. It simply gives
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each record a stable identity.
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---
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## Relationships between tables
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You can link tables together using foreign keys. This is how you express things
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like:
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- A user has many notes
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- A project has many tasks
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- A team has many members
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For example:
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```text
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| id | user_id | content | created_at |
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|----|--------------------------------------|------------------|----------------------|
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| 1 | 9f1b1c94-3e7b-4d6a-9fa7-1e2a3c4ba987 | Buy groceries | 2025-01-10 14:22:11 |
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| 2 | 9f1b1c94-3e7b-4d6a-9fa7-1e2a3c4ba987 | Call the dentist | 2025-01-10 15:08:54 |
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```
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Here, `user_id` refers to a row in a `users` table. This means the note belongs
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to that user, and we can see that this user has two notes.
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Relationships let you organize data without repeating information.
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---
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## Why relational data is useful in practice
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Relational data is really useful in practice because it allows you to:
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- Keep data valid with constraints <br />
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_Example: no duplicate emails._
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- Link records safely with foreign keys <br />
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_Example: delete a user and their notes in one action._
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- Express real permissions with RLS <br />
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_Example: users can read their own notes; admins can read all._
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- Query exactly what you need with table joins <br />
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_Example: fetch notes with the author's email._
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---
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## What we learned
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A database in Supabase is made up of tables.
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Each table has:
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- columns (which describe the type of information stored)
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- rows (the individual pieces of data in that table)
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You can relate tables to each other using foreign keys.
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This lets you model real situations, such as:
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- a user has many notes
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- a team has many members
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- a project has many tasks
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Thinking in tables, rows, and relationships is the foundation of working with data in Supabase.
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