title: PostgreSQL: fill column with quotient of two other columns
body: <p>My PostgreSQL table (scrapes) has a column, which I would like to fill with the quotient of two other columns in the same table. The below didn't work and I am having difficulty finding the right command.</p>
  
  <pre><code>UPDATE scrapes SET priceEUR = sale_price / fxtoEUR;
  </code></pre>
  
  <p>The error message is:</p>
  
  <pre><code>HINT:  Perhaps you meant to reference the column "scrapes.fxtoEUR".
  </code></pre>
  
  <p>The below didn't work either. </p>
  
  <pre><code>SELECT sales_price, fxtoEUR, (sales_price / fxtoEUR) AS priceEUR FROM scrapes;
  </code></pre>
  
  <p>Same error message. Sorry, if this is really obvious, but can't see it right now.</p>