MySQL vs PostgreSQL vs SQL Server: A Comparison

Relational Database Management Systems (RDBMS) play a vital role in application development and data management. Among the most popular RDBMS solutions are MySQL, PostgreSQL, and Microsoft SQL Server. Each has its strengths and ideal use cases depending on the project requirements, performance needs, licensing, and developer preferences.

Overview

• MySQL: An open-source RDBMS, widely used in web applications, especially those developed with PHP and LAMP stack.
• PostgreSQL: A powerful open-source object-relational database system known for standards compliance and extensibility.
• SQL Server: A relational database developed by Microsoft with deep integration into the Windows ecosystem and enterprise applications.

SQL Command Differences & JOIN Support: MySQL vs PostgreSQL vs SQL Server

JOIN Support Overview

All three databases support the following standard SQL JOINs:

• INNER JOIN
• LEFT JOIN / LEFT OUTER JOIN
• RIGHT JOIN / RIGHT OUTER JOIN
• FULL JOIN / FULL OUTER JOIN
• CROSS JOIN
• SELF JOIN

Common SQL Command Differences

Example: Emulating FULL OUTER JOIN in MySQL

SELECT * FROM A
LEFT JOIN B ON A.id = B.id
UNION
SELECT * FROM A
RIGHT JOIN B ON A.id = B.id;
        

Summary

• MySQL is simpler but lacks some advanced JOINs like FULL OUTER JOIN.
• PostgreSQL supports a wide array of SQL standards and offers the most advanced JOIN and JSON features.
• SQL Server includes enterprise-grade commands like MERGE and native FULL OUTER JOIN, and integrates well with Windows services.