Transact-SQL (T-SQL) is an extension of SQL used by Microsoft SQL products and services, including Microsoft SQL Server, and by SAP Adaptive Server Enterprise (SAP ASE). Microsoft states that tools and applications communicating with a SQL Server database do so by sending T-SQL commands.[1] SAP describes its implementation as an enhanced version of the relational database language.[2]
History
In January 1988, Microsoft and Ashton-Tate announced Microsoft SQL Server, based on a relational database management system licensed from Sybase.[3] Sybase Adaptive Server Enterprise was later renamed SAP Adaptive Server Enterprise.[4] Microsoft and SAP publish separate Transact-SQL documentation for their respective database systems.[1][2]
Microsoft implementation
The features described in this section refer to Microsoft's implementation of Transact-SQL.
Variables and control flow
Local variables begin with an at sign (@) and are declared using DECLARE. A newly declared variable has the value NULL. Values can be assigned using SET or SELECT, although Microsoft recommends SET for variable assignment.[5]
Control-flow constructs include BEGIN...END, IF...ELSE, WHILE, BREAK, CONTINUE, RETURN, GOTO, WAITFOR, THROW, and TRY...CATCH.[6]
Stored procedures and error handling
Stored procedures can accept input parameters, return values through output parameters, contain statements that operate on a database, and return a status value to their caller.[7]
The TRY...CATCH construct transfers control to a CATCH block when certain execution errors occur inside its associated TRY block.[8]
Data modification and bulk loading
Transact-SQL extends the DELETE statement with an additional FROM clause, allowing rows to be identified using joined table sources.[9] Its UPDATE statement also accepts a FROM clause containing table, view, or derived-table sources used to determine which rows are updated.[10]
The BULK INSERT statement imports data from a file into a table or view. Depending on the Microsoft database product, the source can be a file accessible to the server or a file in Azure Storage.[11]
See also
References
- 1 2 "Transact-SQL Reference (Database Engine)". Microsoft Learn. Microsoft. Retrieved 31 July 2026.
- 1 2 "Transact-SQL Users Guide". SAP Help Portal. SAP. Retrieved 31 July 2026.
- ↑ "The History of Microsoft – 1988". Microsoft Learn. Microsoft. Retrieved 31 July 2026.
- ↑ "What is Sybase?". SAP. SAP. Retrieved 31 July 2026.
- ↑ "Variables (Transact-SQL)". Microsoft Learn. Microsoft. Retrieved 31 July 2026.
- ↑ "Control-of-Flow". Microsoft Learn. Microsoft. Retrieved 31 July 2026.
- ↑ "CREATE PROCEDURE (Transact-SQL)". Microsoft Learn. Microsoft. Retrieved 31 July 2026.
- ↑ "TRY...CATCH (Transact-SQL)". Microsoft Learn. Microsoft. Retrieved 31 July 2026.
- ↑ "DELETE (Transact-SQL)". Microsoft Learn. Microsoft. Retrieved 31 July 2026.
- ↑ "UPDATE (Transact-SQL)". Microsoft Learn. Microsoft. Retrieved 31 July 2026.
- ↑ "BULK INSERT (Transact-SQL)". Microsoft Learn. Microsoft. Retrieved 31 July 2026.