What is UDF (user-defined function)?
UDF (user-defined function) is a feature of advanced database systems that enables programmers to create custom applications or functions to extend the capabilities of the core database. This enables programmers to use tools such as SQL or JavaScript to create routines and procedures to accomplish tasks such as data transformations, data cleansing or custom logic for complex algorithms.
A programmer creates UDFs to execute a certain process and then call on it each time it is needed. The syntax depends completely on the programming language or application used by the programmer. UDFs are intended to extend database functionality.