What is Transact-SQL

Basic SQL statements, such as SELECT, INSERT, UPDATE, and DELETE are available no matter what relational database system you’re working with. Although these SQL statements are part of the ANSI SQL standard, many database management systems also have their own extensions. These extensions provide functionality not covered by the SQL standard, and include areas such as security management and programmability. Microsoft database systems such as SQL Server, Azure SQL Database, Azure Synapse Analytics, and others use a dialect of SQL called Transact-SQL, or T-SQL. T-SQL includes language extensions for writing stored procedures and functions, which are application code that is stored in the database, and managing user accounts.

SQL is a Declarative language

Programming languages can be categorized as procedural or declarative. Procedural languages enable you to define a sequence of instructions that the computer follows to perform a task. Declarative languages enable you to describe the output you want, and leave the details of the steps required to produce the output to the execution engine.

SQL supports some procedural syntax, but querying data with SQL usually follows declarative semantics. You use SQL to describe the results you want, and the database engine’s query processor develops a query plan to retrieve it. The query processor uses statistics about the data in the database and indexes that are defined on the tables to come up with a good query plan.