//create a new field of the right type in toTable
ensureColumnExists(toTable, colName, nuObjectStack.getRepresentation(toLevel).getReturnType(colName), cw);
IdStatementGenerator idGen = new IdStatementGenerator(adapter, nuObjectStack, true);
int minLevel = Math.min(fromLevel, toLevel);
String idStatement = idGen.generate(minLevel);
StringBuilder sb = new StringBuilder("UPDATE ");
sb.append(toTable);
sb.append(" AS ");
sb.append(toTableAs);
sb.append(" SET ");