Hiring MySQL Developers: The Complete Guide

What MySQL Developers Actually Do

"MySQL Developer" can mean different things depending on your needs:

Application Developers with MySQL Skills

Most common need. These developers:

• Write efficient queries integrated with application code
• Design schemas for web applications
• Understand indexes enough to avoid obvious performance problems
• Use ORMs (Eloquent, ActiveRecord, Sequelize) effectively
• Handle common MySQL-specific features (auto-increment, ENUM types)

Every backend developer working with PHP, WordPress, or many web frameworks should have this level of MySQL knowledge.

Database Engineers / DBAs

Specialized role focusing on:

• Query optimization and performance tuning
• Schema design for complex domains
• Replication, high availability, master-slave setups
• Capacity planning and scaling strategies
• Backup, recovery, and disaster recovery
• MySQL version upgrades and migrations

Needed when your database is a critical bottleneck or you handle high traffic.

WordPress/PHP Developers

Specialized context:

• WordPress database schema and custom tables
• PHP frameworks (Laravel, Symfony) with MySQL
• Plugin and theme database interactions
• WordPress multisite database architecture

Common in content management and PHP-based web applications.

Skill Levels: What to Test For

Level 1: Basic SQL (Every Backend Dev)

• Write SELECT, INSERT, UPDATE, DELETE
• Basic JOINs and aggregations
• Understand primary keys and foreign keys
• Use an ORM correctly
• Basic understanding of indexes

Red flag: Can't write a JOIN without Stack Overflow

Level 2: Competent MySQL User

• Knows when to add indexes (and when not to)
• Understands query execution plans (EXPLAIN)
• Handles transactions and concurrency
• Writes migrations that don't break production
• Understands MySQL-specific features (auto-increment, ENUM, SET types)

This is the minimum for backend developers at your company.

Level 3: MySQL Expert

• Optimizes slow queries systematically
• Designs schemas for complex business domains
• Understands MySQL internals (InnoDB, MyISAM differences)
• Handles replication, partitioning, and high availability
• Can tune MySQL configuration for performance

This is DBA/Database Engineer territory.

Common Use Cases and What to Look For

Web Applications (LAMP/LEMP Stack)

PHP, WordPress, Laravel applications:

• Priority skills: Query optimization, index management, connection pooling
• Interview signal: "How do you handle a slow query in a WordPress site?"
• Red flag: Doesn't know what EXPLAIN shows

E-commerce Platforms

Online stores, marketplaces:

• Priority skills: Transaction handling, inventory management, order processing
• Interview signal: "Design a schema for product variants and inventory"
• Red flag: No understanding of ACID properties

Content Management Systems

WordPress, Drupal, custom CMS:

• Priority skills: Custom table design, WordPress database hooks, multisite architecture
• Interview signal: "How would you optimize WordPress database queries?"
• Red flag: Only knows WordPress admin, no direct database experience

High-Traffic Applications

Social media, SaaS platforms:

• Priority skills: Replication, read replicas, query optimization, caching strategies
• Interview signal: "How would you scale MySQL for 10M+ users?"
• Red flag: Never worked with replication or read replicas

Common Hiring Mistakes

1. Testing Basic SQL Only

Fizz-buzz level SQL (SELECT * FROM users WHERE active = true) doesn't differentiate candidates. Test query optimization, schema design decisions, and handling edge cases.

2. Ignoring Production Experience

Theoretical knowledge differs from battle scars. Ask about production incidents: "Tell me about a database problem you debugged" reveals real experience better than trivia questions.

3. Conflating MySQL with Generic SQL

MySQL has specific features (auto-increment, ENUM types, MyISAM vs InnoDB) that differ from PostgreSQL or SQL Server. If you need MySQL expertise, test for MySQL.

4. Underestimating WordPress/PHP Context

Many MySQL developers work in WordPress/PHP ecosystems. Don't dismiss this experience—it's valuable for many web applications.

5. Overlooking Replication Experience

For scaling, MySQL replication is critical. Candidates who've never set up or maintained replication may struggle with growth.

Interview Approach

For Application Developers

Focus on practical scenarios:

• "Here's a slow page. Walk me through debugging it."
• "Design a schema for [your domain problem]."
• "This query is slow. How would you investigate?"

For Database Engineers/DBAs

Focus on operational knowledge:

• "Walk me through your backup and recovery strategy."
• "How do you handle a table that's grown to 1TB?"
• "Explain MySQL replication and when you'd use it."

Recruiter's Cheat Sheet

Questions That Reveal Skill Level

Resume Green Flags

• Specific performance improvements ("Reduced query time from 30s to 200ms")
• Production scale experience ("Managed 100GB MySQL cluster")
• Mentions specific MySQL features (replication, partitioning, InnoDB tuning)
• Migration experience (version upgrades, schema changes)
• WordPress/PHP ecosystem experience (if relevant)

Resume Red Flags

• Only lists SQL without database-specific experience
• No mention of indexes or performance
• "Expert in databases" but only tutorial projects
• Claims MySQL expertise but only worked with SQLite

MySQL vs PostgreSQL: When to Choose MySQL

MySQL Strengths

• Simplicity: Easier to learn and operate
• Performance: Excellent for read-heavy workloads
• Ecosystem: Massive hosting support, WordPress integration
• Replication: Simple master-slave setup

When MySQL Makes Sense

• WordPress or PHP-based applications
• Simple relational data needs
• Read-heavy workloads
• Teams need something straightforward
• Existing MySQL infrastructure

When to Consider PostgreSQL Instead

• Need advanced features (JSONB, full-text search, PostGIS)
• Complex data relationships
• Write-heavy workloads requiring better concurrency
• Need strict ACID compliance
• Analytical queries with window functions