title: Can't retrieve identity field after insert in sql database
body: <p>Using C++ Qt framework and sql server 2008 I've been trying to insert a record into a table with an identity field and retrieve the identity value. Below is a simplified code sample which actually does do the insert but just doesn't retreive the identity. The identity returned from query.value(0) is an invalid QVariant.</p>
  
  <pre><code>QSqlQuery query(*pConn);
  query.prepare("insert into [VH_MANUFACTURER]  values ('sRRS test man code','RRS type','RRS logo file',1,'RRS SEO para','RRS description','RS');"
  "select SCOPE_IDENTITY();");
  if(query.exec())
  {
      if(query.next())
      {
          QVariant identity =   query.value(0);
          int id=identity.toInt();
      }
  }
  </code></pre>
  
  <p>I've tried using select @@identity instead of scope_identity with no improvement and also  QSqlQuery .lastInsertId() which also returns an invalid QVariant, see below.</p>
  
  <pre><code>  bool bFeature = pConn-&gt;driver()-&gt;hasFeature(QSqlDriver::LastInsertId);
  
  QSqlQuery query(*pConn);
  query.prepare("insert into [VH_MANUFACTURER] ([MFG_NAME],[MFG_TYPE],[MFG_LOGO],[MFG_ACTIVE],[MFG_SEO_CONTENT],[MFG_DESCRI],[MFG_CAPMANCODE]) values ('sRRS test man code','RRS type','RRS logo file',1,'RRS SEO para','RRS description','RS')");
  if(query.exec())
  {
      QVariant id=query.lastInsertId();
  }
  </code></pre>
  
  <p>hasFeature returns true, so the driver is supposed to support what I'm trying to do.
  Just to test the sql , I ran the sql directly through Sql Server Management Studio and it inserts as expected and returns the identity value correctly.</p>