> > since it changed: can I use the procedural languages (any of them) to
> > return a table- (or view-) like output, just like in Interbase, for
> > example? E.g., if I have a metamodel and I want to write functions what
> > perform complex computations and queries, can they return the result
> > (which can be of many rows) to the client?
>
> As of PG 7.2 you can, by returning a cursor:
>
> http://developer.postgresql.org/docs/postgres/plpgsql-cursors.html
If I understand well, I can create a cursor for a SELECT statement, and
return that cursor. Well, it is better than nothing, but I fear it is
not flexible enogh for me.
Here is an example from an interbase app. I have to declare that this is
not my program, and I do not know IB, so forgive me if I say silly
things...
CREATE PROCEDURE VIEW_1_1
(
SZEMPONTID INTEGER,
PARENT CHAR(10) CHARACTER SET WIN1250,
ELNEVEZESTIPUSID INTEGER,
RENDSZERKOD CHAR(16) CHARACTER SET WIN1250
)
RETURNS
(
CHILD VARCHAR(10) CHARACTER SET WIN1250,
GYERMEKDB INTEGER,
OSZTALYTIPUSID INTEGER,
NORMATIVNEV VARCHAR(30) CHARACTER SET WIN1250,
TIPUSNEV VARCHAR(30) CHARACTER SET WIN1250,
NORMATIVKOD VARCHAR(30) CHARACTER SET WIN1250,
TIPUSKOD VARCHAR(30) CHARACTER SET WIN1250
)
AS
BEGIN
FOR
SELECT D1.CHILD, D2.TYPEID
FROM HIERARCHIA D1, OSZTALY D2
WHERE
D1.PARENT = :PARENT AND
D1.SZEMPONTID=:SZEMPONTID AND
D1.CHILD = D2.OSZTALYKOD
ORDER BY D1.SORREND
INTO :CHILD, :OSZTALYTIPUSID
DO
BEGIN
SELECT COUNT(CHILD) FROM HIERARCHIA WHERE PARENT = :CHILD AND
SZEMPONTID = :SZEMPONTID INTO :GYERMEKDB;
EXECUTE PROCEDURE VIEW_ELNEVEZES(:ELNEVEZESTIPUSID, :RENDSZERKOD,
NULL, NULL, NULL, NULL, NULL, :CHILD, NULL)
RETURNING_VALUES :NORMATIVNEV, :TIPUSNEV, :NORMATIVKOD,
:RENDSZERKOD;
SUSPEND;
END
END
The point is not what this proc does (in summary, it gets all the childs
with their properties of a parent in a tree structure), but it cannot
gather all the information with just one select, e.g. it gets some data
from another (nontrivial) stored procedure.
As I see, that 'suspend' command gives back the actual row (and the
control) to the caller until it fetches the next row from this proc's
return value. Do I interpret correct that this stored proc returns a
cursor with structure described in the 'RETURNS' part, and which is not
linked to a SELECT statement?
Can I do something similar in PG? If not now, maybe in the (near)
future?
Thanks:
Circum
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