What Is SQL Server and Why Do You Need It?

Microsoft SQL Server overview

SQL Server is a relational database management system (RDBMS) developed and marketed by Microsoft.

Like other RDBMS products, SQL Server is built on SQL, the standard programming language for interacting with relational databases. SQL Server uses Transact-SQL (T-SQL), Microsoft's proprietary implementation of SQL, which includes additional programming constructs beyond the standard.

For over 20 years, SQL Server ran exclusively on Windows. In 2016, Microsoft made it available for Linux, and SQL Server 2017 became the first version to support both platforms. Below is a brief overview of how it all works.

SQL Server architecture

SQL Server consists of two main components: the Database Engine and the SQL Operating System (SQLOS).

Database Engine

The Database Engine is the core component. It consists of a Relational Engine (which processes queries) and a Storage Engine (which manages database files, pages and indices). Database objects such as stored procedures, views and triggers are also created and executed by the Database Engine.

Relational Engine

Also known as the Query Processor, the Relational Engine determines the most efficient way to execute a query. Its responsibilities include query processing, memory management, thread and task management, buffer management and distributed query processing.

Storage Engine

The Storage Engine is responsible for storing and retrieving data from storage systems such as hard disks and SANs.

SQL Operating System (SQLOS)

Beneath the Relational Engine and Storage Engine sits SQLOS, which provides essential operating system services including memory management, I/O management, exception handling and synchronisation.

SQL Server services and tools

Alongside SQL Server, Microsoft offers a comprehensive set of tools for data management and business intelligence:

  • Data management: SQL Server Integration Services (SSIS), Data Quality Services and Master Data Services
  • Development: SQL Server Data Tools
  • Administration: SQL Server Management Studio (SSMS)
  • Analysis: SQL Server Analysis Services (SSAS)
  • Reporting: SQL Server Reporting Services (SSRS)
  • Machine Learning: Machine Learning Services (introduced in SQL Server 2016, originally called R Services)

SQL Server editions

SQL Server is available in four main editions:

  • Developer Edition (free) -- for database development and testing
  • Express Edition (free) -- for small databases up to 10 GB
  • Standard Edition -- core functionality with some limitations on processor cores and memory
  • Enterprise Edition -- the full feature set for large and mission-critical applications

To find the best prices on all SQL Server editions, visit our SQL Server section. For a detailed comparison, see our guide on SQL Server Standard vs Enterprise.

Want to learn about the latest version? Read our article on SQL Server 2019 features, or browse our server licences for more options including SQL Server 2022 Standard.

If you have any questions, leave us a comment.

Best regards,
The Licendi Team