title: Joining Table that has no value
body: <p>Im working on a friendship site for a client that has been built by another developer. The client has added new questions to the questions table. I can't figure out a query that will return results for all the questions, even for old users who have not answered the new questions. </p>
  
  <p>The issue is that old users dont have an entry in the <strong>user question table</strong> so how can I get a default of 'not answer' for old users who have not input a value in the <strong>user question table</strong>?</p>
  
  <p>See table structure below</p>
  
  <p><strong>User Table</strong></p>
  
  <pre><code>id | username
  0  | louis
  </code></pre>
  
  <p><strong>User Question Table</strong></p>
  
  <pre><code>ID | USERID | Question ID | Answer ID
  0  | 1      | 0           | 5
  1  | 1      | 1           | 8
  </code></pre>
  
  <p><strong>Question Table</strong></p>
  
  <pre><code>ID | QUESTION                    
  0  | What is your favorite color 
  1  | What is your gender         
  2  | What is your favorite t.v. show        
  </code></pre>
  
  <p><strong>Answer Table</strong></p>
  
  <pre><code>ID | answer
  5  | Blue
  8  | female
  </code></pre>
  
  <hr>
  
  <p><strong>This is my desired result:</strong></p>
  
  <pre><code>user       | question                        | answer
  louis      | What is your favorite color     | blue
  louis      | What is your gender             | female
  louis      | What is your height             | Not Answered
  </code></pre>