Amita,
There is now way for DAS to keep the relationship data consistence if
both, pk and fk, are not completely defined. Without them DAS cannot predict
the relationship.
As Brent said, I think it could throw an exception when the PK is missing,
no matter if there are relationships or not. Because, as far as I know, a
table that has no complete PK retrieved on the ResultSet is being omitted
from the graph and I don't think this is a good approach.
But when only the fk is missing, I think it is ok to omit the relationship
between the data objects on the graph. This way the user has the option to
decide if the references(relationships) will be included or not on the
graph.
Regards,
Adriano Crestani
On 7/18/07, Brent Daniel <[EMAIL PROTECTED]> wrote:
Amita,
Definitely, the DAS should enforce the requirement that the PK should
be returned for each table in the results. I would consider this a
case where the DAS should throw an exception.
Brent
On 7/18/07, Amita Vadhavkar <[EMAIL PROTECTED]> wrote:
> Sorry for the leng thy mail....
>
> Tried to check the case when the database has parent-child tables and
DAS
> SELECT Command may/may not
> contain the PKs of the tables. And found some quite confusing
cases/results,
> which are effectively giving
> user a wrong impression of the data in tables.
>
> Looks like there are places where we are allowing partial results, wrong
> association in parent and child rows.
> As RDB DAS logic revolves around PKs, can we state clearly that
> "When Query SELECT does not include PK for a table, the data graph will
be
> empty for that table"
> ? i.e. in the below analysis, instead of giving wrong/partial result, at
> least consistently give no result?
> And make necessary code corrections to adhere to this statement?
>
> Or any alternative approaches?
>
> What DAS C++ is doing for this case? Just curious.
>
-------------------------------------------------------------------------------------
> Say, take below data -
> Parent: SINGER(ID, NAME), Child:SONG (ID, TITLE, SINGERID)
> Data:
> SINGER
> ID NAME
> --------------------
> 1 Jonh
> 2 Jane
>
> SONG
> ID TITLE SINGERID
> -------------------------------------
> 10 ABCD 1
> 20 Lamb 1
> 30 La ra ra 2
>
> There are total 8 cases that I can see. viz.
>
> No relationship in config
> --------------------------------------------------
> parent PK in SEL child PK in SEL Result
> ----------------------------------------------------------------------
> [1] present present correct
> [2] present missing wrong
> [3] missing present wrong
> [4] missing missing wrong
>
> Relationship in config
> [5] present present correct
> [6] present missing wrong
> [7] missing present wrong
> [8] missing missing wrong
>
-------------------------------------------------------------------------------------
> When relationship is not defined in DAS Config
> DAS Client code:
> ----------------
> DAS das = DAS.FACTORY.createDAS(getConfig("cfg.xml"), getConnection());
> Command select = das.getCommand("withNoRel-5/6/7/8");
> DataObject root = select.executeQuery();
> List singers = root.getList("SINGER");
> if(singers != null){
> System.out.println("Singer size:"+singers.size());
> for(int i=0; i<singers.size(); i++){
> System.out.println("SINGER NAME:"+
> ((DataObject)singers.get(i)).getString("NAME"));
> }
>
> }
>
> List songs = root.getList("SONG");//as there is no relationship
> (explicit/implicit)
>
> if(songs != null){
> System.out.println("Songs size "+songs .size());
> for(int ii=0; ii<songs.size(); ii++){
> System.out.println("SONG TITLE:"+
> ((DataObject)songs.get(ii)).getString("TITLE"));
> }
> }
>
> }
>
-------------------------------------------------------------------------------------
> Result:
>
-------------------------------------------------------------------------------------
> [1] SELECT SINGER.ID, SINGER.NAME, SONG.ID, SONG.TITLE FROM SINGER, SONG
> WHERE SINGER.ID = SONG.SINGERID
> Singer size:2
> SINGER NAME:John
> SINGER NAME:Jane
> Songs size 3
> SONG TITLE:ABCD
> SONG TITLE:Lamb
> SONG TITLE:La ra ra
>
> [2] SELECT SINGER.ID, SINGER.NAME, SONG.TITLE FROM SINGER, SONG WHERE
> SINGER.ID = SONG.SINGERID
> Singer size:2
> SINGER NAME:John
> SINGER NAME:Jane
> Songs size 1
> SONG TITLE:ABCD
>
> [3] SELECT SINGER.NAME, SONG.ID, SONG.TITLE FROM SINGER, SONG WHERE
> SINGER.ID = SONG.SINGERID
> Singer size:1
> SINGER NAME:John
> Songs size 3
> SONG TITLE:ABCD
> SONG TITLE:Lamb
> SONG TITLE:La ra ra
>
> [4] SELECT SINGER.NAME, SONG.TITLE FROM SINGER, SONG WHERE SINGER.ID =
> SONG.SINGERID
> Singer size:1
> SINGER NAME:John
> Songs size 1
> SONG TITLE:ABCD
>
-------------------------------------------------------------------------------------
> When relationship one-to-many (sing) is defined in DAS Config
> DAS Client code:
> ----------------
> DAS das = DAS.FACTORY.createDAS(getConfig("cfg.xml"), getConnection());
> Command select = das.getCommand("withRel-1/2/3/4");
> DataObject root = select.executeQuery();
> List singers = root.getList("SINGER");
> if(singers != null){
> System.out.println("Singer size:"+singers.size());
> for(int i=0; i<singers.size(); i++){
> System.out.println("SINGER NAME:"+
> ((DataObject)singers.get(i)).getString("NAME"));
>
> List songs = ((DataObject)singers.get(i)).getList("sing"); //use
> relationship
> if(songs != null){
> System.out.println("Songs size "+songs .size()+" for singer
> :"+((DataObject)singers.get(i)).getString("NAME"));
> for(int ii=0; ii<songs.size(); ii++){
> System.out.println("SONG TITLE:"+
> ((DataObject)songs.get(ii)).getString("TITLE"));
> }
> }
>
> }
> }
>
-------------------------------------------------------------------------------------
> Result:
>
-------------------------------------------------------------------------------------
> [5] SELECT SINGER.ID, SINGER.NAME, SONG.ID, SONG.TITLE FROM SINGER, SONG
> WHERE SINGER.ID = SONG.SINGERID
> Singer size:2
> SINGER NAME:John
> Songs size 2 for singer :John
> SONG TITLE:ABCD
> SONG TITLE:Lamb
> SINGER NAME:Jane
> Songs size 1 for singer :Jane
> SONG TITLE:La ra ra
>
> [6] SELECT SINGER.ID, SINGER.NAME, SONG.TITLE FROM SINGER, SONG WHERE
> SINGER.ID = SONG.SINGERID
> Singer size:2
> SINGER NAME:John
> Songs size 0 for singer :John
> SINGER NAME:Jane
> Songs size 1 for singer :Jane
> SONG TITLE:ABCD
>
> [7] SELECT SINGER.NAME, SONG.ID, SONG.TITLE FROM SINGER, SONG WHERE
> SINGER.ID = SONG.SINGERID
> Singer size:1
> SINGER NAME:John
> Songs size 3 for singer :John
> SONG TITLE:ABCD
> SONG TITLE:Lamb
> SONG TITLE:La ra ra
>
> [8] SELECT SINGER.NAME, SONG.TITLE FROM SINGER, SONG WHERE SINGER.ID =
> SONG.SINGERID
> Singer size:1
> SINGER NAME:John
> Songs size 1 for singer :John
> SONG TITLE:ABCD
>
-------------------------------------------------------------------------------------
>
> Regards,
>
> Amita
>
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