title: How to write an "exclusive" query in SQL?
body: <p>I am going over a past paper for a database course I am taking and I am stuck on an SQL question</p>
  
  <p>Here is the schema provided</p>
  
  <ul>
  <li><p>Country(name, capital, area), name is the key</p></li>
  <li><p>People(country, population, children, adult) where country refers to the
  name in Country, population is the total population, and children and adult
  is the percentage of the children and adult population.</p></li>
  <li><p>Language(country,language,percentage) – for each language spoken in the
  country, it lists the percentage of the population that speaks the language.</p></li>
  </ul>
  
  <p>Here is the question:</p>
  
  <blockquote>
    <blockquote>
      <p>Write the following query in SQL: Find languages that are <em>only</em> spoken in countries whose total population exceeds 10^7.</p>
    </blockquote>
  </blockquote>
  
  <p>This is what I have so far:</p>
  
  <pre><code>SELECT l.language
  FROM people p, language l
  WHERE l.country = p.country AND
      p.population &gt; 10^7
  </code></pre>
  
  <p>The bit I am confused about is how to check that there are no other countries which a language is spoken in but the population is less than 10^7.</p>
  
  <p>Any advice?
  Thanks</p>