List thisSymbols = getSymbols();
List copySymbols = new ArrayList(thisSymbols.size());
Iterator iter = thisSymbols.iterator();
while(iter.hasNext()) {
SelectSymbol ss = (SelectSymbol) iter.next();
copySymbols.add(ss.clone());
}
Select copy = new Select(copySymbols);
copy.setDistinct( isDistinct() );
return copy;