Database Reference
In-Depth Information
CQL - the Cassandra Query Language
Since this is a topic about Cassandra and not targeted to users of any particular program-
ming language or application framework, we will focus entirely on the database interac-
tions that MyStatus will require. Code examples will be in
Cassandra Query Language
(
CQL
). Specifically, we'll use version 3.1.1 of CQL, which is available in Cassandra 2.0.6
and later versions.
As the name implies, CQL is heavily inspired by SQL; in fact, many CQL statements are
equally valid SQL statements. However, CQL and SQL are not interchangeable. CQL lacks
a grammar for relational features such as JOIN statements, which are not possible in Cas-
sandra. Conversely, CQL is not a subset of SQL; constructs for retrieving the update time
of a given column, or performing an update in a lightweight transaction, which are avail-
able in CQL, do not have an SQL equivalent.
Note
Throughout this topic, you'll learn the important constructs of CQL. Once you've com-
pleted reading this topic, I recommend you to turn to the DataStax CQL documentation for
additional reference. This documentation is available at
http://www.datastax.com/docu-
