Transact-SQL (T-SQL) is Microsoft and Sybase’s extension to the SQL (Structured Query Language) used to interact with relational databases. T-SQL expands on the SQL standard to include procedural programming, various support functions for string processing, local variables, data processing, mathematics and changes to the DELETE and UPDATE statements.
Transact-SQL is central to using Microsoft SQL Server. All applications that communicate with a SQL Server do so by sending Transact-SQL statements to the server, regardless of the user interface of the application.
Transact-SQL identifiers, meanwhile, are used in all databases, servers, and database objects in SQL Server. These include tables, constraints, views, columns, stored procedures, and data types. Each Transact-SQL identifiers must have a unique name which is assigned when an object is created and is used to identify an object.
Many IT professionals will be aware of T-SQL, however roles such as .Net Software Developers and Application Support Analysts are more likely to utilise it within their work.