title: How to get distinct value from repeating result
body: <p>I have a table like name 'items'</p>
  
  <pre><code>id      sender  receiver        item
  1       1       2               computer
  2       2       1               mobile
  3       1       3               ipad
  4       4       1               ring
  5       3       1               camera
  6       1       8               pc
  7       5       1               ring
  8       1       10              tablet
  </code></pre>
  
  <p>I only can do these two queries like</p>
  
  <pre><code>SELECT `receiver` FROM `items` WHERE `sender` ='1' 
  </code></pre>
  
  <p>result</p>
  
  <pre><code>2
  3
  4
  10
  </code></pre>
  
  <p>and</p>
  
  <pre><code>SELECT `sender` FROM `items` WHERE `receiver` ='1'
  </code></pre>
  
  <p>result</p>
  
  <pre><code>2
  4
  3
  5
  </code></pre>
  
  <p>How can I get distinct recevier/sender(count only one, if comes more than 1) where sender/receiver=1</p>
  
  <p>like bellow</p>
  
  <pre><code>2
  3
  4
  5
  10
  </code></pre>