Microsoft SQL Server vs MySQL vs PostgreSQL: What are the differences?

Introduction

Microsoft SQL Server, MySQL, and PostgreSQL are three popular and widely used relational database management systems (RDBMS). While all three are capable of handling large amounts of data and offer various features, there are several key differences that set them apart.

1. Data Types and Functions: Microsoft SQL Server, MySQL, and PostgreSQL offer different data types and functions. For example, Microsoft SQL Server has its own unique data types like datetime2 and money that are not available in MySQL and PostgreSQL. Similarly, MySQL has its own data types like ENUM and SET which are not found in the other two database systems. Additionally, each RDBMS has its own set of built-in functions that may differ from one another.

2. Transaction Management: While all three database systems support transactions, there are differences in how they handle them. Microsoft SQL Server uses the BEGIN TRANSACTION, COMMIT, and ROLLBACK statements to manage transactions. On the other hand, MySQL and PostgreSQL use the START TRANSACTION, COMMIT, and ROLLBACK statements. Additionally, PostgreSQL supports savepoints within a transaction, which allows for more granular control over transaction rollback.

3. Concurrency Control: Concurrency control is the ability of a database system to handle multiple transactions concurrently while maintaining data consistency. Microsoft SQL Server, MySQL, and PostgreSQL use different methods to achieve concurrency control. SQL Server uses locking and multiversion concurrency control (MVCC) to manage concurrency. MySQL primarily relies on locking, but it also supports MVCC for some storage engines. PostgreSQL is known for its advanced MVCC implementation, allowing for higher concurrency and better scalability.

4. Replication: Replication is the process of copying and synchronizing data across multiple database instances. Microsoft SQL Server, MySQL, and PostgreSQL offer different replication options. SQL Server has its own replication technology, which allows for various types of replication, such as snapshot replication and transactional replication. MySQL provides replication capabilities through its native MySQL replication, which supports master-slave replication. PostgreSQL also supports master-slave replication, but it also offers more advanced options like logical replication and high availability solutions.

5. Stored Procedures and Triggers: All three database systems support the use of stored procedures and triggers. However, there are differences in their implementation and syntax. Microsoft SQL Server uses Transact-SQL (T-SQL) for stored procedures and triggers, while MySQL uses its own dialect of SQL, which is similar to standard SQL. PostgreSQL supports stored procedures and triggers using various languages, including PL/pgSQL (similar to Oracle's PL/SQL) and other scripting languages like Python and Perl.

6. Licensing and Cost: Another significant difference between the three database systems is the licensing and cost. Microsoft SQL Server is a commercial product and requires the purchase of licenses, which can be costly depending on the edition and number of user licenses needed. MySQL and PostgreSQL, on the other hand, are open-source and free to use, making them more cost-effective options for many organizations.

In Summary, Microsoft SQL Server, MySQL, and PostgreSQL differ in data types and functions, transaction management, concurrency control, replication options, stored procedures and triggers syntax, as well as licensing and cost.