title: SQL select multiple columns to return one distinct field
body: <p>I am looking to return a (single) column that has the distinct values of 4 columns that I will be looking up within the same table.</p>
  
  <p>I've tried </p>
  
  <pre><code>"select distinct e1l,e2l,e1s,e2s from jobmovement"
  </code></pre>
  
  <p>but this is just returning each distinct occurrence of the four tables, so for example if there were 4 lines of 178,178,178,178  it would just return 1 of these.</p>
  
  <p>So for example, I have 4 column headers (E1L,E2L,E1S,E2S):</p>
  
  <p><code>E1L,E2L,E1S,E2S</code></p>
  
  <p><code>178,178,178,178
     ,   ,216,216
     ,178,   ,
  217,217,178,216</code> </p>
  
  <p>I would this to return in the single column the distinct values</p>
  
  <pre><code>178
  216
  217
  </code></pre>
  
  <p>Any help would be appreciated.
  Thanks, Paul.</p>