What is "tsql"
T-SQL (Transact Structured Query Language) is the extension of SQL functionality supported by Sybase ASE and Microsoft SQL Server. They share the name because Microsoft SQL Server was based on Sybase ASE code in a partnership that later dissolved. Although the name is shared, the functionality is not necessarily identical. With the introduction of Microsoft SQL Server 2005, the SQL Server code has been completely rewritten to provide . Net integration.
Transact-SQL is key to using Microsoft SQL Server. All applications that communicate with an instance of SQL Server do so by sending Transact-SQL instructions to the server, regardless of the application user interface.
Questions about T-SQL should be marked appropriately with any sql-server or Sybase, and include the version as well.
More information can be found at T-SQL SQL Server and Sybase Transact-SQL User Guide.