According to Wikipedia, Transact-SQL, sometimes abbreviated T-SQL, is Microsoft's and Sybase's proprietary extension to the SQL language. Microsoft's implementation ships in the Microsoft SQL Server product. Sybase uses the language in its Adaptive Server Enterprise, the successor to Sybase SQL Server. In order to make it more powerful, SQL has been enhanced with additional features such as:

* Control-of-flow language - Like BEGIN and END, BREAK, CONTINUE, GOTO, IF and ELSE, RETURN, WAITFOR, and WHILE statements.

* Local variables - Like DECLARE and SET statements

* Various support functions for string processing, date processing, mathematics, etc. - Like SIN(), ASIN(), LOG(), etc.

* Improvements to DELETE and UPDATE statements - Both the DELETE and UPDATE statements allow a FROM clause to be added which allows joins to be included.