Question: I would like to have a Joomla site send queries to an external database (via API) and then return the query results and display them in Joomla. I cannot find a book or tutorial that explains Joomla development in enough detail to figure out how to do this.  

Can someone recommend a book or tutorial to get me started? Thanks

Answer: 
If you are integrating a database, supported by a Joomla driver, you can simply call if via JDatabaseDriver:

[Connecting to an external database](https://docs.joomla.org/Connecting_to_an_external_database)

```
<?php
$option = array(); //prevent problems

$option['driver']   = 'mysql';            // Database driver name
$option['host']     = 'db.myhost.com';    // Database host name
$option['user']     = 'fredbloggs';       // User for database authentication
$option['password'] = 's9(39s£h[%dkFd';   // Password for database authentication
$option['database'] = 'bigdatabase';      // Database name
$option['prefix']   = 'abc_';             // Database prefix (may be empty)

$db = JDatabaseDriver::getInstance( $option );
?>

```

Otherwise, you have to install and develop with a specific PHP library, beyond Joomla supported drivers.
If you want to integrate the results with Joomla search, a good starting point would be reading the [Joomla tutorial for search plugins](https://docs.joomla.org/J3.x:Creating_a_search_plugin).

If you want to have it separate from other search, you may want to create a module or even a light weight component. There are lots of components and plugins that allow you to add your own PHP code to a page. Sourcerer is one often mentioned.

The starting point though should be studying this unnamed API so you can do the search and get result. The rest is relatively trivial other than having to choose the method you want to use to make the results visible to in Joomla! to match your unspecified needs.