Yes, if table2.table1_id is declared as a foreign key in the database schema,
then generate_mapping will automatically produce the output you want.
Maybe your database doesn't declare any foreign keys? This is common in MySQL
databases, because until a few years ago MySQL didn't support checking of
foreign keys. You should be able to check by running “SHOW CREATE TABLE
table2;” in MySQL.
Best,
Richard
> On 20 Dec 2013, at 07:59, "Fabian Cretton" <fabian.cret...@hevs.ch> wrote:
>
> Thank you Richard, maybe I don't see it.
>
> I have a situation like this:
> table1.id (the primary key)
> table1.name
>
> table2, which primary key is:
> table1.id
> timestamp
>
> It does generate (simplified example):
> map:table2_table1_id a d2rq:PropertyBridge;
> d2rq:column "table2.table1_id";
> d2rq:datatype xsd:integer;
>
>
> Here is a very standard SPARQL query for me:
> select *
> {
> ?aTable2Instance a table2;
> hereALinkToTable1 ?table1Instance.
> ?table1Instance name ?name.
> }
>
> In order to do such a query, I obviously can't use the "table2_table1_id"
> property bridge which just gives me an ID.
>
> I thus linked the table 2 to table 1 manually, by defining:
> map:table2_table1 a d2rq:PropertyBridge;
> d2rq:property vocab:table2_table1;
> d2rq:refersToClassMap map:table1;
> d2rq:join "table2.table1_id => table1.id";
>
> Do you mean that the generate-mapping tool handle this automatically and I
> didn't find it ?
>
> Thank you
> Fabian
>
>
>
>>>> Richard Cyganiak <rich...@cyganiak.de> 19.12.2013 11:58 >>>
> Fabian,
>
> On 19 Dec 2013, at 09:40, "Fabian Cretton" <fabian.cret...@hevs.ch> wrote:
>
>
>
> As far as I can see, the default generate-mapping tool don't link the
> instances of the tables which are linked by foreign keys.
>
>
> It does generate links for any foreign keys declared in the DB schema.
>
> Best,
> Richard
>
>
>
>
>
>
> Is it right that we have to manually create all those links as described
> here:
> http://d2rq.org/d2rq-language#example-refers
>
> Is it something that could be easily automated, but was just not useful so
> far ?
>
> Thank you
> Fabian
>
>
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