Skip to content

Home / 001_Getting_Started_with_SQL_Server / 001.001.What_is_SQL_Server

001.001. What is SQL Server

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

Like other RDBMS platforms, SQL Server is built on SQL (Structured Query Language), the standard language for querying and managing relational databases. SQL Server uses Transact-SQL (T-SQL), Microsoft’s proprietary extension to SQL, which includes additional programming constructs.

Initially exclusive to Windows for over 20 years, SQL Server 2017, released in October 2017, was the first version to support both Windows and Linux environments.

SQL Server Architecture

The following diagram illustrates the architecture of the SQL Server:

SQL Server Architecture

SQL Server architecture is composed of two main components:

  • Database Engine
  • SQLOS (SQL Server Operating System)

1. Database Engine

The Database Engine is the core of SQL Server. It includes:

  • Relational Engine: Also known as the query processor, it determines the optimal method to execute queries. It handles:

    • Memory management
    • Thread and task management
    • Buffer management
    • Distributed query processing

  • Storage Engine: Manages the storage and retrieval of data. It interacts with physical storage systems suchs as disks and Storage Area Networks (SANs).

The Database Engine also creates and manages database objects such as:

  • Stored procedures
  • Views
  • Triggers

2. SQLOS

SQLOS sits beneath the Relational and Storage Engines, providing essential operating system-level services, including:

  • Memory management
  • I/O management
  • Exception handling
  • Synchronization services

SQL Server Services and Tools

Microsoft bundles SQL Server with a suite of data management and business intelligence (BI) tools.

Data Management Tools

  • SQL Server Integration Services (SSIS)
  • SQL Server Data Quality Services
  • SQL Server Master Data Services

Development and Management Tools

  • SQL Server Data Tools (SSDT) – for database development
  • SQL Server Management Studio (SSMS) – for managing, deploying, and monitoring databases

Analytics and Reporting Tools

  • SQL Server Analysis Services (SSAS) – for online analytical processing (OLAP)
  • SQL Server Reporting Services (SSRS) – for reporting and data visualization
  • Machine Learning Services – introduced in SQL Server 2016 (originally as R Services)

SQL Server Editions

SQL Server comes in several editions tailored to different needs. The main editions include:

Free Editions

  • Developer Edition: Full-featured, for development and testing only.
  • Express Edition: Lightweight, ideal for small applications. Limited to 10 GB of storage.
  • Enterprise Edition: Full set of features for mission-critical applications and large-scale performance.
  • Standard Edition: Subset of Enterprise features. Includes limitations on:
    • Number of processor cores
    • Memory capacity

For more details, refer to the SQL Server 2022 Editions documentation.