title: SQL - Create view from multiple tables
body: <p>I have three tables:</p>
  
  <pre><code>POP(country, year, pop)
  FOOD(country, year, food)
  INCOME(country, year, income)
  </code></pre>
  
  <p>I am trying to create a view such as:</p>
  
  <pre><code>V(country, year, pop, food, income)
  </code></pre>
  
  <p>This is my code so far. I don't think its correct:</p>
  
  <pre><code>CREATE VIEW V AS
  (SELECT * FROM POP
  UNION
  SELECT * FROM FOOD
  UNION
  SELECT * FROM INCOME);
  </code></pre>
  
  <p>One issue is, a country that is present in <code>POP</code> may not be present in <code>FOOD</code>. Same goes for year. A year that is present in <code>POP</code> may not be present in <code>FOOD</code>. So, I keep thinking that the above code will not work.</p>