How to fix ERROR 1364: Field doesn't have a default value in MySQL

ERROR 1364 (HY000): Field 'username' doesn't have a default value

-- WRONG (missing username):
INSERT INTO users (id, email) VALUES (1, '[email protected]');

-- CORRECT (all NOT NULL columns included):
INSERT INTO users (id, username, email) VALUES (1, 'john_doe', '[email protected]');

-- Or use column order explicitly:
INSERT INTO users (id, username, email, created_at) 
VALUES (1, 'john_doe', '[email protected]', NOW());

-- Check current column definition:
SHOW COLUMNS FROM users WHERE Field = 'username';

-- Add a default:
ALTER TABLE users MODIFY username VARCHAR(255) NOT NULL DEFAULT 'anonymous';

-- For timestamp columns:
ALTER TABLE users MODIFY created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP;

-- For numeric columns:
ALTER TABLE users MODIFY status INT NOT NULL DEFAULT 0;

-- Modify an existing column:
ALTER TABLE users MODIFY user_id INT NOT NULL AUTO_INCREMENT UNIQUE;

-- Or during table creation:
CREATE TABLE users (
  user_id INT NOT NULL AUTO_INCREMENT,
  username VARCHAR(255) NOT NULL,
  email VARCHAR(255) NOT NULL,
  PRIMARY KEY (user_id)
);

-- Now you can insert without specifying user_id:
INSERT INTO users (username, email) VALUES ('john_doe', '[email protected]');

// Node.js / Express example:
// WRONG:
const user = await User.create({ email: '[email protected]' });

// CORRECT:
const user = await User.create({
  username: 'john_doe',
  email: '[email protected]',
  status: 1
});

# Python / SQLAlchemy example:
# CORRECT:
user = User(username='john_doe', email='[email protected]', status=1)
db.session.add(user)
db.session.commit()

-- View full table structure:
DESC users;
-- or:
SHOW CREATE TABLE users\G

-- Check specific column:
SHOW COLUMNS FROM users WHERE Field = 'username';

-- The "Null" column shows "NO" for NOT NULL
-- The "Default" column shows any default value, or NULL if none