/** modifies SelectQuery to order result set
\param f field to order by
\param asc ascending order
\return *this, methods can be chained */
DataSource& orderBy(FieldType f, bool asc=true) {
sel.orderBy(f.fullName(), asc);
return *this;
}
/** modifies SelectQuery to order result set by external table
\param id foreign key field used to join table with query
\param f field to order by
\param asc ascending order
\return *this, methods can be chained */
DataSource& orderByRelation(FieldType id, FieldType f, bool asc=true) {
sel.source(id.table());
sel.where(id == T::Id);
sel.orderBy(f.fullName(), asc);
return *this;
}
