ExoSQL

Not everything described here is working yet

Universal SQL engine for Elixir.

This library implements the SQL logic to perform queries on user provided databases using a simple interface based on Foreign Data Wrappers from PostgreSQL.

This allows to use SQL on your own data.

For example it is included a CSV reader and an HTTP client, so that you can do queries as:

SELECT url, LENGTH(content), status_code
  FROM urls
  INNER JOIN http
  ON urls.url = http.url

Installation

The package can be installed by adding exosql to your list of dependencies in mix.exs:

def deps do
  [
    {:exosql, "~> 0.1.0"}
  ]
end

Features

• SELECT over external databases
• SELECT over several tables
• WHERE
• GROUP BY
• Some aggregation functions: COUNT, SUM, AVG

Check the tests for current features available.

INNER JOIN [WIP]

Because some columns may need to be autogenerated depending on the query, if you want to access those columns you may need to use INNER JOINS. This way the planner asks for those specific column values.

For example:

SELECT * FROM http

does not know to which URL you want to access, but:

SELECT * FROM http WHERE url = 'http://serverboards.io'

knows the URL and can get the data.

Teh same way, on INNER JOINS this can be used to access to autogenerated data:

SELECT url, LENGTH(content), status_code
  FROM urls
  INNER JOIN http
  ON urls.url = http.url