A user-defined function (UDF) is a function provided by the user of a program or environment, in a context where the usual assumption is that functions are built into the program or environment. Although the term is widely known in Hadoop components such Hive and Pig, it is also used in other contexts such programming languages and some DBMSs.

- Stackoverflow.com Wiki
1 articles, 0 books.

Like most databases created in the last few decades, SQL Server allows developers to extend the database by creating functions. But prior to the upcoming 2019 release, SQL Server’s support for scalar functions was fraught with problems.