Query.StringDefines field subscripting syntax.
It is also possible to reference a field of a column by the column's number in the selection. For example, in a query
select (from students $ students)
~join:[[field name]]
~where:(id.[0] <> id.[1])a variable id.[0] will be bound to the field id of the first column of a selection, and id.[1] will be bound to the second one.