Using queries to retrieve data from connected tables
<h3>What I want to do:</h3>

<p>I would like to retrieve all data fields about a <code>Customer</code>(including all data from tables that are related with him (e.g the data fields of the <code>Country</code> &amp; data fields of the <code>referralagent</code></p>

<p>I'd like my query to take as a parameter the <code>idUser</code>.</p>

<hr>

<p><strong>Here is my EER Diagram:</strong></p>

<p><a href="https://i.stack.imgur.com/koVd5.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/koVd5.png" alt="EER Diagram"></a></p>

<hr>

<p><strong>What I tried:</strong></p>

<pre><code>SELECT
referralagent.firstName
,referralagent.lastName
,customer.firstName
,customer.lastName
,customer.address
,customer.postcode
,customer.profession
,customer.phoneNumWork
,customer.phoneNumMobile
,customer.phoneNumHome
,country.name
,nationality.name

    FROM 
        customer
        INNER JOIN referralagent
            ON customer.ReferralAgent_idreferralAgent = referralagent.idReferralAgent
        INNER JOIN country
            ON customer.countryResidence = country.idCountry
        INNER JOIN nationality
            ON customer.nationality = nationality.idNationality

            WHERE customer.idUser = '7'
</code></pre>

<p><strong>The question:</strong></p>

<p>I'm not confident that what I tried is something that's "correct". Is there
any better way to do it?</p>