SQL Server - Introduction
Microsoft SQL Server is a relational database management system (RDBMS) developed by Microsoft. A relational database organizes data into data tables in which data types may be related to each other. These relations help structure the data. Transact-SQL (T-SQL) is an extension of SQL that is used in SQL Server. Transact-SQL is closely integrated into the SQL language, yet it adds programming constructs that are not native to SQL. As a database server, it is a software product with the primary function of storing and retrieving data as requested by other software applications which may run either on the same computer or another computer across a network (including the Internet).
Microsoft SQL Server comes in several versions, each corresponding to various workloads and demands. The data center edition is optimized for higher application support and scalability levels, while the Express edition is a free, scaled-down version of the software. Some important features of SQL Server are given below:
SQL Server Features:
- SQL Server is a software, developed by Microsoft, which is implemented from the specification of a relational database management systems (RDBMS).
- SQL Server is used to build and maintain databases.
- SQL Server is used to analyze the data using SQL Server Analysis Services (SSAS).
- SQL Server is used to generate reports using SQL Server Reporting Services (SSRS).
- SQL Server is used to perform ETL operations using SQL Server Integration Services (SSIS).
- SQL Server is both GUI and command based software.
- SQL Server is platform dependent.
- It allows to install multiple versions on a single computer, each of which operates independently of the others.
SQL Server Instances
An instance is the installation of SQL Server. Multiple instances of SQL Server can be installed on a particular machine, but only one can be the default. It is an exact copy of the server files, databases, and security credentials.
SQL Server is divided into two types:
Primary Instances: A primary instance can be accessed in two ways. The first is by using the server name, and the second is its IP address. It is always unique.
Named Instances: A named instance can be accessed by appending a backslash and instance name.
For example, suppose that It is required to connect with an instance named XXX on the local server, we need to use 127.0.0.1\XXX. On a server running SQL Server 2005 or later, we can run up to 50 instances at the same time.