Auto Increment

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ELI5 — The Vibe Check

Auto increment means the database assigns the next ID number automatically every time you insert a row. You insert user #1, #2, #3 without ever thinking about it. No need to track 'what was the last ID' yourself.

Real Talk

Auto increment is a column property (SERIAL or IDENTITY in PostgreSQL, AUTO_INCREMENT in MySQL) that generates a unique, sequential integer value for each new row. It is the most common implementation for surrogate primary keys. The sequence is managed by the database engine.

Show Me The Code

-- PostgreSQL (SERIAL)
CREATE TABLE users (
  id SERIAL PRIMARY KEY  -- 1, 2, 3...
);

-- MySQL
CREATE TABLE users (
  id INT AUTO_INCREMENT PRIMARY KEY
);

When You'll Hear This

"The id column auto-increments so you never have to set it manually." / "Gaps in auto-increment IDs are normal — don't worry about them."

Related Terms

Default Value

A default value is what gets stored in a column when you do not provide one.

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Primary Key

A primary key is the unique ID that every row in a table must have. Like a social security number for your data — no two rows can have the same one.

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UUID (Universally Unique Identifier)

A UUID is a randomly generated ID that looks like 'a3b4c5d6-...' and is practically guaranteed to be unique across the entire universe.

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