title: QtSQL: "prepared statement "qpsqlpstmt_1" does not exist" on clear() of model
body: <p>I am getting the following error message printed in the console:</p>
  
  <pre><code>Unable to free statement: ERROR:  prepared statement "qpsqlpstmt_1" does not exist
  </code></pre>
  
  <p>It is printed when the the following function is called in the application (or when the object is deleted (if <code>clear()</code> is not called before delete):</p>
  
  <pre><code>sqlQueryModel-&gt;clear();
  </code></pre>
  
  <p>sqlQueryModel object is of type <code>QSqlQueryModel</code> and is used throughout a derived class to communicated with a PostgreSQL database. It also serves as a model for <code>QCompleter</code>. I have never declared or used the name <code>"qpsqlpstmt_1"</code>.</p>
  
  <p>Could someone help me interpret the error message please, and explain what might be causing it? Is this indicative of a problem in my code or a Qt bug? (likely the former :))</p>
  
  <p>On reviewing the PostgreSQL log file on the server, the exact same statement appears plus an additional line:</p>
  
  <pre><code>STATEMENT: DEALLOCATE pqsqlpstmt_1
  </code></pre>