Transact-SQL（又称T-SQL），是在Microsoft SQL Server和Sybase SQL Server上的ANSI SQL实作，与Oracle的PL/SQL性质相近（不只是实作ANSI SQL，也为自身数据库系统的特性提供实作支持），目前在Microsoft SQL Server和Sybase Adaptive Server中仍然被使用为核心的查找语言。

Transact-SQL是具有批次与区块特性的SQL指令集合，数据库开发人员可以利用它来撰写数据部份的商业逻辑（Data-based Business Logic），以强制限制前端应用程序对数据的控制能力。同时，它也是数据库对象的主要开发语言。

Transact-SQL (T-SQL) is Microsoft's and Sybase's proprietary extension to SQL. SQL, the acronym for Structured Query Language, is a standardized computer language that was originally developed by IBM for querying, altering and defining relational databases, using declarative statements. T-SQL expands on the SQL standard to include procedural programming, local variables, various support functions for string processing, date processing, mathematics, etc. and changes to the DELETE and UPDATE statements. These additional features make Transact-SQL Turing complete.