T-SQL - Introduction

Microsoft T-SQL 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 T-SQL. 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 T-SQL 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 T-SQL are given below:

T-SQL Features:

T-SQL Instances

An instance is the installation of T-SQL. Multiple instances of T-SQL 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.

T-SQL 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 XYZ on the local server, we need to use 127.0.0.1\XYZ. On a server running T-SQL 2005 or later, we can run up to 50 instances at the same time.