Using existing database
=======================

Let's say you have a Postgres database with data in it, and you'd like to get instant GraphQL on it.

This section assumes that you already have Hasura and Postgres setup.

As a tutorial, this section will use a sample dataset that we'll import to see how Hasura works with existing databases.

Step 1 (optional): Import a sample dataset
------------------------------------------

You can skip this step if your Postgres database already has data.

Let's use the `Chinook database <https://raw.githubusercontent.com/xivSolutions/ChinookDb_Pg_Modified/pg_names/chinook_pg_serial_pk_proper_naming.sql>`_ as an example.

.. code-block:: bash

  $ wget https://raw.githubusercontent.com/xivSolutions/ChinookDb_Pg_Modified/pg_names/chinook_pg_serial_pk_proper_naming.sql
  $ psql --echo-errors -h 127.0.0.1 -p 5432 -U postgres -d postgres < chinook_pg_serial_pk_proper_naming.sql
  ..
  ..
  ..
  CREATE INDEX
  CREATE TRIGGER
  CREATE TRIGGER
  ALTER TABLE
  CREATE INDEX
  CREATE TRIGGER
  ALTER TABLE

Step 2: Open the hasura console
-------------------------------

Now, open the hasura console:

.. code-block:: bash

  # Run this command in the my-project/ directory
  $ hasura console

Navigate to `http://localhost:9695/data/schema <http://localhost:9695/data/schema>`_

You should see the list of tables which are yet to be tracked in your public schema. It should look like the screenshot below

.. image:: ../../../img/graphql/manual/getting-started/UntrackedTables.jpg
  :alt: List of untracked tables

Click on the ``Add all`` button as shown in the image below to track all the tables.

.. image:: ../../../img/graphql/manual/getting-started/TrackTable.jpg
  :alt: Track the list of untracked table

Once all the tables are tracked, you'll see that tables come up in the sidebar:

.. image:: ../../../img/graphql/manual/getting-started/TableTracked.jpg
  :alt: Tables successfully tracked


Now we have successfully tracked the tables, let's open API Explorer and make a GraphQL query:


.. image:: ../../../img/graphql/manual/getting-started/GraphQLAPI.jpg
  :alt: Make a simple fetch call to query actors

.. code-block:: graphql

  # Query                  |            # Response
  query {                  |            {
    actors {               |              "data": {
      id                   |                "actors": [
      first_name           |                  {
      last_name            |                    "id": 1,
    }                      |                    "first_name": "Penelope",
  }                        |                    "last_name": "Guinness"
                           |                  },
                           |                  // ...
                           |                ]
                           |              }
                           |            }