Accessing geometric values from embedded SQL

Hi,
I'm really stuck with this one, so any help greatly appreciated....

If I create a table BBoxes with the definition:

create table BBoxes(
    bbox box
);

that is suitably initialised with boxes, then issue the following sql
embedded in C:

    EXEC SQL BEGIN DECLARE SECTION;
            char ret_bbox[500];
    EXEC SQL END DECLARE SECTION;

    strcpy(query_string, "(1,1),(5,5)");

    EXEC SQL DECLARE bbox_curs CURSOR FOR SELECT bbox FROM BBoxes;
    exec sql whenever not found do break;
    EXEC SQL OPEN bbox_overlaps_curs;

    for(;;) {
        EXEC SQL FETCH bbox_overlaps_curs into :ret_bbox;
    }

I get the following problems:

1) ret_bbox always contains an empty string
2) the fetch operation's sqlca.sqlcode always is -211 (DATA_NOT_ARRAY)


I've also tried (in desperation) declaring the cursor as:

EXEC SQL DECLARE bbox_curs CURSOR FOR SELECT box(bbox) FROM BBoxes;

I've also (again in desperation) tried the following:

    exec sql type POINT is struct { double x; double y; };
    exec sql type BOX is struct { POINT high; POINT low; };
    EXEC SQL BEGIN DECLARE SECTION;
            BOX ret_bbox;
    EXEC SQL END DECLARE SECTION;


with the same code, and still get the -211 error, and the fields of
ret_bbox, containing gibberish.

Any ideas about how to do this, or how to do this with ADTs in general
would be appreciated.

Many thanks,

--
Tony

---------------------------------
Dr. Tony Griffiths
Research Fellow
Information Management Group,
Department of Computer Science,
The University of Manchester,
Oxford Road,
Manchester M13 9PL,
United Kingdom

Tel. +44 (0) 161 275 6139
Fax +44 (0) 161 275 6236
email tony.griffiths@cs.man.ac.uk
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