How to Create a User-Defined Function (UDF) in Relational Database

Including how to use, alter, and remove UDF using SQL Server

Table of Contents

• Introduction
• Advantages of UDF
• UDF in SQL Server
∘ Create or Modify a UDF
∘ Remove UDFs
• Examples
∘ Creating database
∘ UDF examples
• Try It Yourself
• Summary
• References

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Introduction

User-defined functions (UDF) are functions created by users in a relational database. UDF allows users to create custom functions that can be used within SQL statements to manipulate data, perform custom calculations, or return desired results.

Here are some things to know about UDF.

Custom function creation
UDF allows users to create custom functions according to their needs. This function can be a scalar function that returns a single value, a table function that returns a data set, or an aggregate function that returns an aggregated value from a data group.