===============
MySQL Connector
===============

The MySQL connector allows querying and creating tables in an external
MySQL database. This can be used to join data between different
systems like MySQL and Hive, or between two different MySQL instances.

Configuration
-------------

To configure the MySQL connector, create a catalog properties file
in ``/etc/opt/prestoadmin`` named, for example, ``mysql.properties``, to
mount the MySQL connector as the ``mysql`` catalog.
Create the file with the following contents, replacing the
connection properties as appropriate for your setup:

.. code-block:: none

    connector.name=mysql
    connection-url=jdbc:mysql://example.net:3306
    connection-user=root
    connection-password=secret

Use ``presto-admin`` to deploy the connector file. See :doc:`../installation/presto-admin/installation/presto-catalog-installation`.
    
Multiple MySQL Servers
^^^^^^^^^^^^^^^^^^^^^^

You can have as many catalogs as you need, so if you have additional
MySQL servers, simply add another properties file to ``/etc/opt/prestoadmin``
with a different name (making sure it ends in ``.properties``). For
example, if you name the property file ``sales.properties``, Presto
will create a catalog named ``sales`` using the configured connector.

Querying MySQL
--------------

The MySQL connector provides a schema for every MySQL *database*.
You can see the available MySQL databases by running ``SHOW SCHEMAS``::

    SHOW SCHEMAS FROM mysql;

If you have a MySQL database named ``web``, you can view the tables
in this database by running ``SHOW TABLES``::

    SHOW TABLES FROM mysql.web;

You can see a list of the columns in the ``clicks`` table in the ``web`` database
using either of the following::

    DESCRIBE mysql.web.clicks;
    SHOW COLUMNS FROM mysql.web.clicks;

Finally, you can access the ``clicks`` table in the ``web`` database::

    SELECT * FROM mysql.web.clicks;

If you used a different name for your catalog properties file, use
that catalog name instead of ``mysql`` in the above examples.

MySQL Connector Limitations
---------------------------

The following SQL statements are not yet supported:

* :doc:`/sql/delete`
* :doc:`/sql/alter-table`
* :doc:`/sql/create-table` (:doc:`/sql/create-table-as` is supported)
* :doc:`/sql/grant`
* :doc:`/sql/revoke`