MySQL Cheat Sheet

MySQL cheat sheet with real commands and snippets for setup, core workflows, debugging, and production-safe automation patterns. If you are working across tools, pair this with the SQL Cheat Sheet and SQLite Cheat Sheet.

Setup and Connection

Goal: Connect to database shell or endpoint

# Run connection or version command
mysql -u root -p

# Run connection or version command
mysql -h 127.0.0.1 -u app -p appdb

# Run connection or version command
mysql --version

Schema and Data Modeling

Goal: Create a table/index/schema foundation

-- Create UTF-8 table with proper defaults
CREATE TABLE users (
  id BIGINT UNSIGNED AUTO_INCREMENT PRIMARY KEY,
  email VARCHAR(255) NOT NULL UNIQUE,
  created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

Core Queries and Mutations

Goal: Run practical read/write operations

-- Paginate results with deterministic ordering
SELECT id, email, created_at
FROM users
ORDER BY id DESC
LIMIT 50 OFFSET 0;

Performance and Optimization

Goal: Add indexes and inspect query plans

-- Add index and inspect query plan
CREATE INDEX idx_users_created_at ON users(created_at);
EXPLAIN SELECT * FROM users WHERE created_at >= NOW() - INTERVAL 30 DAY;

Automation and Backups

Goal: Create backup and restore routines

# Export data snapshot before risky migrations
pg_dump "$DATABASE_URL" > backup.sql || mysqldump appdb > backup.sql || true

# Compress backup artifact for storage
gzip -f backup.sql || true

# Verify backup file exists and has content
ls -lh backup.sql.gz || ls -lh backup.sql

Debugging and Troubleshooting

Goal: Inspect slow-query symptoms

# Check active connections/sessions
psql -c "SELECT now();" || mysql -e "SELECT NOW();" || true

# Inspect query plans for heavy statements
psql -c "EXPLAIN SELECT 1;" || mysql -e "EXPLAIN SELECT 1;" || true

# Search migration files for destructive statements
rg "DROP TABLE|TRUNCATE|DELETE FROM" prisma migrations sql -n

Common Gotchas

• Use transactions for multi-step MySQL data changes that must stay consistent.
• Create indexes for frequent WHERE and JOIN columns, then verify with query plans.
• Back up production data before schema migrations.
• Separate read-only credentials from write credentials in app environments.
• Monitor connection pool limits to avoid timeout spikes under load.

Related Sheets

• SQL Cheat Sheet — query patterns, joins, and data analysis.
• SQLite Cheat Sheet — daily SQLite commands and production-ready examples.
• GraphQL Cheat Sheet — daily GraphQL commands and production-ready examples.