CQL
===

The ``gt-cql`` module a human readable "Contextual Query Language" for writing filter expressions
for working with geospatial information.

CQL was originally known as Common Query Language (so you will find lots of examples that still
refer to this name). The standard comes out of library science and was picked up by the OGC when
they were implementing their catalog server specification.

.. image:: /images/gt-cql.png

For our purposes it provides a great human readable way to expression Filter similar to an
SQL "where clause". Indeed we have our own extension that allows you to represent the full
range of GeoTools Filter and Expression ideas using simple text strings.

**References**

* http://en.wikipedia.org/wiki/Contextual_Query_Language
* http://www.opengeospatial.org/standards/specifications/catalog

**Maven**::
   
    <dependency>
      <groupId>org.geotools</groupId>
      <artifactId>gt-cql</artifactId>
      <version>${geotools.version}</version>
    </dependency>

**Contents**

.. sidebar:: Details
   
   .. toctree::
      :maxdepth: 1
      
      faq
      internal

.. toctree::
   :maxdepth: 1
   
   cql
   ecql
