title: How to session variable work with IN clause using MySQL?
body: <p>I want to know how session variables work with <code>IN</code> clause using MySQL.</p>
  
  <p>I tried this myself but seriously not success.</p>
  
  <p>Queries with session variables </p>
  
  <pre><code>SET @concat_var := (SELECT GROUP_CONCAT(player_id) FROM tableB where id = 1);
  // result 88,89
  SELECT @concat_var;
  SELECT player_id FROM tableA WHERE player_id IN (@concat_var);
  </code></pre>
  
  <p>Query Output (<em>not accurate</em>)</p>
  
  <pre><code>player_id 
  88
  </code></pre>
  
  <p>(<em>Result required</em>)</p>
  
  <pre><code>player_id 
  88 
  89   
  </code></pre>