Microsoft SQL Server 2008 R2 Transact-SQL Language 10.50.1750.9

Transact-SQL is supported on Microsoft SQL Server 2000, Microsoft SQL Server 2005, Microsoft SQL Server 2008, Microsoft SQL Server 2008 R2, Microsoft SQL Server 2012, Microsoft SQL Server 2014, and Microsoft SQL Server 2016.

Transact-SQL is Microsoft's implementation of the Structured Query Language (SQL) with extensions that add programming constructs such as variables, control-of-flow statements, and error handling to the language.

Some key features of Transact-SQL include support for stored procedures, triggers, user-defined functions, and views; the ability to work with temporary tables and table variables; and support for transactions and isolation levels.

A stored procedure in Transact-SQL is a precompiled set of one or more SQL statements that are stored on the server and can be executed as a unit. Stored procedures can be used to improve performance by reducing network traffic, improving security by limiting direct access to tables, and promoting code reuse.

A trigger in Transact-SQL is a special kind of stored procedure that executes automatically whenever certain events occur on a table or view, such as updates, inserts, or deletes. Triggers can be used to enforce business rules or apply complex integrity constraints.

User-defined functions in Transact-SQL are similar to stored procedures but return a value rather than a result set. They can be used to encapsulate complex business logic or calculations, and can be called from other Transact-SQL statements.

A view in Transact-SQL is a virtual table that is based on the result set of a SELECT statement. Views can be used to simplify queries by abstracting away complexity or joining tables together, and can also be used to provide an additional layer of security by limiting access to certain rows or columns.

Temporary tables and table variables in Transact-SQL are used to store data temporarily within a session or a batch. They are typically used when intermediate results need to be stored for further processing, or when complex algorithms require many iterations of data manipulation.

Transaction management in Transact-SQL refers to the ability to group one or more SQL statements together into a single, atomic unit of work that either succeeds or fails as a whole. This ensures data integrity and consistency, and allows for complex operations involving multiple statements to be performed safely and reliably.

Transact-SQL supports four isolation levels: READ UNCOMMITTED, READ COMMITTED, REPEATABLE READ, and SERIALIZABLE. These isolation levels control the visibility of changes made by concurrent transactions, and can affect the performance, concurrency, and consistency of the database.