SQL Server is a relational database management system (RDBM) developed by Microsoft that competes with Oracle, IBM DB2, MySQL, PostgreSQL, and other RDBMs. In this article, I’ll explain in detail what is SQL Server and go through its release history over the past three decades. I’ll also detail what are the different SQL Server versions you can download and use today.
SQL Server is an enterprise relational database platform, and its main purpose is to provide a data store for various applications and services. In the past, RDBMs were primarily for online transaction processing (OLTP) applications like order entry, invoicing, shipping, and retail sales. However, the scope of relational database systems has evolved over time.
They are now the backend for most websites as well as the data store for business intelligence and online analytical processing (OLAP) decision support applications. Modern enterprise data platforms like SQL Server also have ties to Big Data and NoSQL datastores as well.
The SQL Server enterprise data platform supports several different languages for various functions, but the primary two are T-SQL (Transact-SQL) and MDX (Multidimensional Expressions). T-SQL is a proprietary extension of the standard ANSI SQL (Structure Query Language) language.
SQL uses data definition language (DML) statements to create database objects and data manipulation language (DDL) statements to query data. The vast majority of SQL Server queries, stored procedures, triggers, and functions are written using T-SQL. MDX is a query language developed by Microsoft for OLAP queries and processing OLAP cubes.
SQL Server is managed using SQL Server Management Studio (SSMS).
SQL Server has been around for quite a while. SQL Server 1.0 was originally released in partnership with Sybase back in 1989. That partnership ended in 1992 with the release of SQL Server 4.2.
SQL Server was originally an application for the OS/2 operating system. OS/2 was dropped in favor of Windows for most of the later releases of SQL Server. More modern releases have added Linux support. Today the most recent release of SQL Server is SQL Server 2022.
You can see a timetable of the different SQL Server releases in the following listing:
SQL Server is released in the following editions:
You can install SQL Server 2022 on Windows, a virtual machine on Azure, Linux, and Docker containers. You can check out our previous tutorial for installing SQL Server on Windows with the typical setup configuration.
Since SQL Server 2017, Microsoft has offered a Linux version of its relational database platform. Microsoft did this by abstracting the operating system calls in the SQL Server engine and then implementing a translation layer in the SQL Server architecture called SQLPAL, which acts as an SQL Server operating system layer.
As you might guess, while the core database capabilities are the same, there are differences between the Linux version of SQL Server 2022 and the Windows version. Most of these differences are found in the supporting subsystems and services. SQL Server 2022 is officially supported on the following Linux distributions.
To go further, please check out our tutorial showing how to Install SQL Server 2022 and Azure Data Studio on Linux.
Today’s SQL Server is far more than just a relational database engine. SQL Server is a complete enterprise data platform supporting a wide variety of data storage and query methods that provide RDBM services, analytics, data integration, as well as reporting capabilities. Let’s take a closer look at the different subsystems, components, and services that are a part of SQL Server 2022.
SQL Server 2022 provides the following major subsystems:
SQL Server provides a set of services that provide interfaces for different management and development functions. The different services include:
As you might expect from an enterprise-level data platform, SQL Server supports several different business continuity features. Here are the main high-availability features you should know about.
SQL Server Failover Clustering uses a Windows Server clustered environment to switch all processing from a primary node to a backup node if the current server node becomes unavailable. Failover clustering requires shared or local storage and virtual network resources. It provides high availability but does not support load-balancing.
Always On availability groups (AGs) are part of the SQL Server Enterprise, Developer, and Evaluation editions and they provide high availability and disaster recovery for groups of databases that can fail over together. AGs provide support for high availability and disaster recovery, and backups can be performed on a secondary replica.
Only available in the SQL Server Standard edition, Basic Always On availability groups provide a high availability solution for SQL Server Standard Edition for versions 2016 and newer. These groups provide availability at the database level, they only support a single database. There is no support for read-scale implementations or backups on a secondary replica.
Primarily a disaster recovery technology, Log Shipping allows you to automatically send transaction log backups from a primary database on an SQL Server instance to one or more secondary databases on secondary server instances. The transaction log backups can be applied to each of the secondary databases individually.
SQL Server also provides a number of different integration points with the Microsoft Azure cloud. Some of the primary cloud integration features include:
Microsoft also offers SQL Server relational database services in the Azure cloud. To learn more you can check out Azure SQL Database.
In this article, I detailed the overall purpose and functions of Microsoft SQL Server. I also gave you an overview of its release history, the editions of SQL Server provided in the current SQL Server 2022 release, as well as its major subsystems and services.
Overall, I only covered the major features of SQL Server, but as you might guess there are many more features that provide additional database services. This “SQL Server Essential” series is not over yet, so keep an eye on Petri for more information about Microsoft’s enterprise relational database platform.