SQL Server

Microsoft SQL Server

Pronunciation: SEE-kwul SUR-ver or ess-kyoo-EL SUR-ver

Updated October 3, 20262 min read

In short

Microsoft SQL Server is Microsoft's relational database, queried with the T-SQL dialect of SQL and widely used for business apps alongside .NET and Windows.

What is SQL Server?

SQL Server's first version appeared in 1989, developed with Sybase, and it has been one of the major commercial databases ever since. It stores data in tables with full ACID transactions and is queried with T-SQL (Transact-SQL), Microsoft's extension of standard SQL with variables, procedural logic, error handling and many built-in functions.

Beyond the core engine, SQL Server ships with tools for business data: Integration Services for ETL jobs, Reporting Services for reports, Analysis Services for OLAP models, and columnstore indexes for fast analytics. SQL Server Management Studio and Azure Data Studio are the usual tools for working with it.

It comes in several editions, including the free Express and Developer editions and the paid Standard and Enterprise editions. Since SQL Server 2017 it also runs on Linux and in Docker containers, and Microsoft offers it as managed cloud services, Azure SQL Database and Azure SQL Managed Instance.

A common misconception is that SQL Server only works with Microsoft technologies. It is common with .NET, but drivers exist for Java, Python, Node.js, Go and others, and it runs on Linux. Licensing for the larger editions can be expensive, which is why many new projects compare it with free alternatives such as PostgreSQL.

Key takeaways

SQL Server is Microsoft's relational database, first released in 1989.
It is queried with T-SQL, Microsoft's extended SQL dialect.
Tools for ETL, reporting and analytics come with it.
Since 2017 it also runs on Linux and in containers.
Express and Developer editions are free; Azure SQL is the cloud version.

Example

A T-SQL query with a variable and paginationsql

DECLARE @Since date = '2026-01-01';

SELECT TOP (10)
    c.CustomerId,
    c.Name,
    SUM(o.Total) AS Revenue
FROM dbo.Customers AS c
JOIN dbo.Orders AS o ON o.CustomerId = c.CustomerId
WHERE o.OrderDate >= @Since
GROUP BY c.CustomerId, c.Name
ORDER BY Revenue DESC;

-- Paging with OFFSET/FETCH
SELECT Name FROM dbo.Customers ORDER BY Name
OFFSET 20 ROWS FETCH NEXT 10 ROWS ONLY;

Readers ask

Is SQL Server free?

The Express edition is free with limits on database size and resources, and the Developer edition is free with all features for development and testing. Production use of Standard or Enterprise requires a license.

What is T-SQL?

Transact-SQL, SQL Server's dialect of SQL. It adds variables, control flow, error handling and many functions to standard SQL, and is used in queries, stored procedures and scripts.

SQL Server or PostgreSQL?

Both are mature relational databases. SQL Server integrates closely with Microsoft tools and offers built-in business intelligence services; PostgreSQL is free, open source and highly extensible. Cost and the existing technology stack usually decide.