What is the difference between SQL Server and MySQL?

SQL Server and MySQL are both relational database management systems, but they differ in licensing, features, and ecosystem. SQL Server is a commercial product developed by Microsoft, primarily designed for Windows environments, though it now supports Linux. MySQL, originally open-source and now owned by Oracle, is cross-platform and widely used in web applications. The most immediate difference is cost: SQL Server requires paid licenses for full features, while MySQL offers a free community edition. For example, SQL Server’s Enterprise Edition includes advanced analytics and high availability tools but comes with significant licensing fees, whereas MySQL’s free tier is sufficient for many small-to-medium projects.

Technically, the two systems use slightly different SQL dialects and feature sets. SQL Server uses Transact-SQL (T-SQL), which includes proprietary extensions like stored procedures with error handling (TRY...CATCH) and window functions (ROW_NUMBER()). MySQL uses standard SQL with some extensions, like the IF() function or ENGINE clauses for specifying storage engines. For instance, string concatenation in SQL Server uses +, while MySQL requires the CONCAT() function. SQL Server also integrates tightly with Microsoft tools like Power BI and Azure, while MySQL often pairs with PHP or Linux-based stacks. Additionally, SQL Server provides built-in reporting services (SSRS) and ETL tools (SSIS), which MySQL lacks natively, requiring third-party solutions like Tableau or Pentaho.

Use cases often dictate the choice between the two. SQL Server suits enterprises needing advanced security (e.g., row-level security, Always Encrypted) or Windows-centric environments. For example, a company using Active Directory might prefer SQL Server for integrated authentication. MySQL is ideal for cost-sensitive or open-source-focused projects, such as web apps using LAMP (Linux, Apache, MySQL, PHP) stacks. MySQL also supports more storage engines (InnoDB, MyISAM) for flexibility in balancing speed and reliability. While SQL Server excels in complex enterprise workloads, MySQL’s simplicity and scalability make it a default choice for startups or applications requiring horizontal scaling via sharding or replication.