I do something like what is shown below, but if you have an updatable view (using multiple tables) on your database then something similar to this snippet should work.
Qt Code: 
  1. void homestead::UpdateProperty() {
  2. 	QDateTime dtNow = QDateTime::currentDateTime();
  3. 	QString propQryPrep = "UPDATE property_";
  4. 	propQryPrep.append(this->dbYear);
  5. 	propQryPrep.append(" SET \
  6. 					   county     = :county, \
  7. 					   cntyname   = :cntyname, \
  8. 					   txdistrict = :txdistrict, \
  9. 					   legal      = :legal, \
  10. 					   parcel_id  = :parcel_id, \
  11. 					   pvalue     = :pvalue, \
  12. 					   entry_id   = :entry_id, \
  13. 					   entry_date = :entry_date, \
  14. 					   notes      = :notes \
  15. 					   WHERE proprty_id = :proprty_id");
  16.  
  17. 	propQry.prepare(propQryPrep);
  18. 	propQry.bindValue(":county",ui.leCountyNumber->text().toInt());
  19. 	propQry.bindValue(":cntyname",ui.cboCountyName->currentText());
  20. 	propQry.bindValue(":txdistrict",ui.leTaxDistrict->text());
  21. 	propQry.bindValue(":legal",ui.txtLegal->toPlainText());
  22. 	propQry.bindValue(":parcel_id",ui.leParcelID->text());
  23. 	propQry.bindValue(":pvalue",ui.leHomeValue->text().toInt());
  24. 	propQry.bindValue(":entry_id",homestead::RevID);
  25. 	propQry.bindValue(":entry_date",dtNow);
  26. 	propQry.bindValue(":notes",ui.teNotes->toPlainText());
  27. 	propQry.bindValue(":proprty_id",ui.leProprtyID->text().toInt());
  28. 	if (propQry.exec()) {
  29. 		ui.leStatus->setText("Property record: "+ui.leProprtyID->text()+" updated!");
  30. 	} else {
  31. 		ui.leStatus->setText("Cannot updated property record: "+ui.leProprtyID->text());
  32. 	}
  33. }
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BTW, this code works on Oracle and on PostgreSQL before 8.1.0. On PostgreSQL after 8.0 they've added 3 millisecond positions to the QDateTime return.