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

Similar to other RDBMS software, SQL Server is built on top of SQL, a standard programming language for interacting with relational databases. SQL Server is tied to Transact-SQL, or T-SQL, Microsoft’s implementation of SQL, which includes a set of proprietary programming constructs.

SQL Server has been exclusively available on the Windows environment for over 20 years. In 2016, Microsoft made it available on Linux. SQL Server 2017 became generally available in October 2016 and was compatible with both Windows and Linux.

SQL Server consists of two main components:

Database Engine

The core component of the SQL Server is the Database Engine, which comprises a relational engine that processes queries and a storage engine that manages database files, pages, indexes, etc.

Additionally, the database engine creates database objects such as stored procedures, views, and triggers.

Relational Engine

The Relational Engine contains the components that determine the optimal method for executing a query. It is also known as the query processor.

The relational engine requests data from the storage engine based on the input query and processes the results.

Some tasks of the relational engine include querying 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 the storage systems such as disks and SAN.