private String orderBy() {
StringBuffer buffer = new StringBuffer();
boolean isHead = true;
// make group by field
for (Field field : orderField) {
if (field.isOrderBy()) {
if (isHead) {
isHead = false;
buffer.append(ORDER_BY);
} else {
buffer.append(",");
}
buffer.append(field.getFieldName());
}
}
return buffer.toString();
}
