Re: SQL in R2RML mappings

>
> The main idea here is that the predicate to be used for a column-value in a
> row is obtained from the value in another column. That is, the predicate is
> not just a constant URI.
>
>     rr:predicateObjectMap
>     [
>       rr:predicateMap [ rr:column "empLikes" ];
>       rr:objectMap    [ rr:column "likedObj" ]
>     ]
>
>
Souri - This example is very close to what I am describing with this
difference: I am describing a case where a RefPredicateObjectMap is used to
tie the subject of one TriplesMap to the subject of another TriplesMap.



> Is this the kind of scenario you are thinking about?
>

Yes, except for the case I am describing there would not be sufficient data
in the WORKS table to produce the URI for the person. Like this:

 PERSON Table (used in a Triplesmap TM1):
<person_id, name,      age>
---------------
100    John            29
200    Brad           35

WORKS Table (used in TriplesMap TM2):
<person_id,   activity,          item>
----------------------------------
100      composed      "Rock Song"
100      wrote             "Java Book"
200      composed      "Pop Song"

Then I want to express a RefPredicateObjectMap on TM1 like this:

<http://mine/RefPredicateObjectMap>
    rr:refPredicateMap [rr:template "http://..parent.{activity}"]; # Is this
allowed?
    rr:refObjectMap [
        rr:parentTriplesMap TM2;
        rr:joinCondition "child.{person_id} = parent.{person_id}" ];
.

In this example, I want the RefPredicateMap to refer to the "activity"
column in the logical table of the "parent" TriplesMap. Is this allowed?

Thank you?

-David