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Couchbase Essentials

Couchbase Essentials

By : John C Zablocki
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Couchbase Essentials

Couchbase Essentials

3 (2)
By: John C Zablocki

Overview of this book

This book is for those application developers who want to achieve greater flexibility and scalability from their software. Whether you are familiar with other NoSQL databases or have only used relational systems, this book will provide you with enough background to move you along at your own pace. If you are new to NoSQL document databases, the design discussions and introductory material will give you the information you need to get started with Couchbase.
Table of Contents (10 chapters)
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9
Index

Aggregation and math


Performing aggregation is also a familiar operation. To write a query to count the number of breweries by state, you use the built-in count aggregate function:

SELECT state, COUNT(*) AS Count
FROM beer-sample
WHERE type = "brewery"
GROUP BY state

As you might expect, N1QL supports mathematical and aggregate operations such as AVG, ROUND, MIN, MAX, and SUM. You can use these operations to perform calculations on either aggregated data or on projected columns. As another example of aggregation with N1QL, this query computes the average abv (alcohol by volume) of a brewery's beer brands:

SELECT brewery_id, AVG(abv) AS Average
FROM beer-sample
WHERE type = "beer"
AND abv != 0 
GROUP BY brewery_id

Similarly, if you want to find the beer with the highest or lowest alcohol content, you can use the MAX or MIN function respectively. In the following snippet, the HAVING clause is added to the GROUP BY clause to filter the results:

SELECT name, MAX(abv) AS Strength
FROM beer-sample...

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