Learning CodeQL
###############

CodeQL is the code analysis platform used by security researchers to automate variant analysis. 
You can use CodeQL queries to explore code and quickly find variants of security vulnerabilities and bugs. 
These queries are easy to write and share–visit the topics below and `our open source repository on GitHub <https://github.com/Semmle/ql>`__ to learn more. 
You can also try out CodeQL in the `query console <https://lgtm.com/query>`__ on `LGTM.com <https://lgtm.com>`__. 
Here, you can query open source projects directly, without having to download CodeQL databases and libraries. 

CodeQL is based on a powerful query language called QL. The following topics help you understand QL in general, as well as how to use it when analyzing code with CodeQL.

.. pull-quote::

   Important 

   If you've previously used QL, you may notice slight changes in terms we use to describe some important concepts. For more information, see our note about :doc:`Recent terminology changes <terminology-note>`.

.. toctree::
   :hidden:

   terminology-note
   

.. _getting-started:

Getting started
***************

If you are new to QL, start by looking at the following topics:

.. toctree::
   :maxdepth: 1

   introduction-to-ql
   about-ql
   beginner/ql-tutorials
   ql-etudes/river-crossing

CodeQL training and variant analysis examples
*********************************************

To start learning how to use CodeQL for variant analysis for code written in a specific language, see:

.. toctree::
   :maxdepth: -1

   ql-training

.. _writing-ql-queries:

Writing CodeQL queries
**********************

To learn more about writing your own queries, see:

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   :maxdepth: 3
   :includehidden:

   writing-queries/writing-queries

For more information on using CodeQL to query code written in a specific language, see:

.. toctree::
   :maxdepth: 2
   :includehidden:

   cpp/ql-for-cpp
   csharp/ql-for-csharp
   cobol/ql-for-cobol
   go/ql-for-go
   java/ql-for-java
   javascript/ql-for-javascript
   python/ql-for-python

Technical information
*********************

For more technical information see:

.. toctree::
   :maxdepth: 2
   :includehidden:

   technical-info    

Reference topics
****************

For a more comprehensive guide to the query language itself, see the following reference topics: 

- `QL language handbook <https://help.semmle.com/QL/ql-handbook/index.html>`__—a description of important concepts in QL.
- `QL language specification <https://help.semmle.com/QL/ql-spec/language.html>`__—a formal specification of QL.

Search
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.. * :ref:`genindex` remove index for the time being as we currently have no tags

* :ref:`search`
