Transact SQL

Microsoft’s and Sybase’s proprietary extension of the SQL standard, serving as the primary programming language for interacting with SQL Server to perform queries, data manipulation, and database administration.

• Procedural programming: T-SQL extends ANSI SQL with procedural features such as variables, conditional statements (IF/ELSE), loops (WHILE), error handling (TRY/CATCH), and stored procedures.
• Database administration: DBAs use T-SQL to create and modify database objects (DDL), manage security through GRANT, REVOKE, and DENY, query Dynamic Management Views (DMVs), and develop maintenance scripts.
• Advanced features: >T-SQL includes capabilities such as Common Table Expressions (CTEs), window functions (OVER/PARTITION BY), dynamic SQL using sp_executesql, PIVOT/UNPIVOT, and JSON/XML data processing.
• Application logic: Stored procedures, user-defined functions, and views are core building blocks of SQL Server applications. DBAs should understand how different T-SQL coding patterns affect query performance and scalability.
• Best practice: Use parameterized queries, such as stored procedures or sp_executesql, instead of dynamic string concatenation to improve execution plan reuse and protect against SQL injection attacks.
• Related terms: Dynamic SQL, Query, SQL Server Management Studio, Execution Plan.