For beginners

What is a relational database, really?

Mental model:

MariaDB stores those "files", lets many programs read/write at once safely, survives power loss, and is queried with SQL.

Your first table

CREATE DATABASE blog;
USE blog;

CREATE TABLE posts (
  id          BIGINT AUTO_INCREMENT PRIMARY KEY,
  title       VARCHAR(200)  NOT NULL,
  body        TEXT,
  author      VARCHAR(64)   NOT NULL,
  created_at  DATETIME      DEFAULT CURRENT_TIMESTAMP,
  INDEX idx_author (author)
);

INSERT INTO posts (title, body, author)
VALUES ('Hello', 'First post', 'alice'),
       ('Another', 'Written by AI', 'bob');

SELECT * FROM posts WHERE author = 'alice';

Top beginner pitfalls

1. Use utf8mb4, never utf8. The legacy utf8 only stores 3 bytes/char — no emoji, no rare Han glyphs.
2. Primary keys: BIGINT AUTO_INCREMENT or UUID v7. Don't use business fields (email, phone) — they change.
3. Don't index every column. Indexes speed reads but slow writes and take space.
4. Don't forget COMMIT in transactions.
5. Don't use MyISAM. No transactions, not crash-safe. Default to InnoDB.

Next

• For AI developers
• On the cloud
• Operations