Book Image

Learning Azure DocumentDB

By : Riccardo Becker
Book Image

Learning Azure DocumentDB

By: Riccardo Becker

Overview of this book

Learning DocumentDB adopts a practical, step-by-step approach to help you learn the basics of DocumentDB and use your new-found abilities in real-life scenarios and enterprise solutions. We start with the absolute basics, such as setting up a DocumentDB environment, and guide you through managing your databases, and executing simple and complex queries. Next, we explain how to work with DocumentDB using the open REST protocol, and demonstrate how JavaScript works with DocumentDB. We’ll also show you how to authenticate and execute queries. Moving on, you’ll find out how to use DocumentDB from within Node.js to kick-start your Node.js projects. Next, you’ll discover how to increase the performance of your DocumentDB database and fine-tune it. Finally, you’ll get to grips with using DocumentDB in conjunction with other services offered from the Microsoft Azure platform.
Table of Contents (15 chapters)
Learning Azure DocumentDB
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Building user-defined functions


A UDF can be used to write custom business logic. UDFs can only be called from inside queries. A good example of a UDF inside our domain is produced by creating a function that calculates the price of a device including VAT.

UDFs can be created on the Azure portal, just like stored procedures and triggers. This UDF can be defined in the following way:

If the VAT exceeds 100 percent, the function just returns the price (the VAT is then probably invalid or a mistake). Otherwise, it returns the original price including VAT. Testing this UDF involves a simple query.

The UDF can also be included inside WHERE clauses of our queries.