title: MySQL query to count occurence of specific column value relating to id column
body: <p>I'm wondering how to do a MySQL query that counts how many times a certain column value appears. For example I have a table with various columns, i'm interested in the id and prop_id columns. I want to count how many times a prop_id is 2, in relation to each id. </p>
  
  <pre><code>id - prop_id
  1  - a
  1  - b
  2  - c
  3  - b
  3  - b
  3  - c
  </code></pre>
  
  <p>The results of my query would be: </p>
  
  <pre><code>id - count(prop_id)
  1 - 1
  2 - 0
  3 - 2
  </code></pre>
  
  <p>I'm having trouble translating this into a query despite it probably being fairly simple. I'm sure my terminology is off too, my knowledge of MySql is fairly basic, for now.</p>