title: ERROR at line 1: ORA-00937: not a single-group group function
body: <p>On this I am getting an error </p>
  
  <blockquote>
    <p>ERROR at line 1:
    ORA-00937: not a single-group group function. </p>
  </blockquote>
  
  <p>Can someone help me on this I am not familiar on <code>sql</code>. </p>
  
  <pre><code>select cerps_accnt_code, cost_centre, SUM(TOTAL_AMOUNT_DUE) 
  from globe_billing_report where tag like '%Duncan%'
  </code></pre>