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Learning Apache Cassandra

You're reading from   Learning Apache Cassandra Build an efficient, scalable, fault-tolerant, and highly-available data layer into your application using Cassandra

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Product type Paperback
Published in Feb 2015
Publisher
ISBN-13 9781783989201
Length 246 pages
Edition 1st Edition
Languages
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Author (1):
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Matthew Brown Matthew Brown
Author Profile Icon Matthew Brown
Matthew Brown
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Table of Contents (14) Chapters Close

Preface 1. Getting Up and Running with Cassandra 2. The First Table FREE CHAPTER 3. Organizing Related Data 4. Beyond Key-Value Lookup 5. Establishing Relationships 6. Denormalizing Data for Maximum Performance 7. Expanding Your Data Model 8. Collections, Tuples, and User-defined Types 9. Aggregating Time-Series Data 10. How Cassandra Distributes Data A. Peeking Under the Hood B. Authentication and Authorization Index

Updating the existing rows


Now that we've got a new location column, we can add some data to it. Any new user records we create, of course, can have a location value, but perhaps some of our existing users would like to input their location value too. To do this, we need to be able to update existing rows. The process should, once again, look quite familiar to anyone who is familiar with SQL:

UPDATE "users"
SET "location" = 'New York, NY'
WHERE "username" = 'alice';

Like the INSERT and DELETE statements, the UPDATE statement does not give us any feedback on the operation. However, we can confirm it worked by reading from the users table again:

SELECT * FROM "users";

As we hoped, alice now has a location:

Note

A full reference for the UPDATE statement can be found in the DataStax CQL documentation at http://www.datastax.com/documentation/cql/3.1/cql/cql_reference/update_r.html

Updating multiple columns

As in the SQL UPDATE statement, we can specify multiple column-value pairs to be updated in a...

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