Thread: pl/pgsql capabilities?
Hi all, A long time ago (at version 6.3.2 or what :) I have asked, but maybe 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? Thank you: Circum
On Mon, Jul 01, 2002 at 01:43:29AM +0200, Ferenc Engard wrote: > Hi all, > > A long time ago (at version 6.3.2 or what :) I have asked, but maybe > 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 -Roberto -- +----| http://fslc.usu.edu/ USU Free Software & GNU/Linux Club |------+ Roberto Mello - Computer Science, USU - http://www.brasileiro.net/ http://www.sdl.usu.edu/ - Space Dynamics Lab, Developer I wonder if Singapore has any computer pirateers or hackers...
> > 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 SETWIN1250 ) RETURNS ( CHILD VARCHAR(10) CHARACTER SET WIN1250, GYERMEKDB INTEGER, OSZTALYTIPUSID INTEGER, NORMATIVNEV VARCHAR(30) CHARACTER SETWIN1250, 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=:SZEMPONTIDAND 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
On Tue, Jul 02, 2002 at 01:37:08AM +0200, Ferenc Engard wrote: > > 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. Maybe not for the solution you have right now, but you most likely can rework things a bit to make it work. > 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 > ) ... > 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? Not in the way you currently have, as far as I could understand it. I didn't read the procedure very attentively because it's horribly written in all caps, and my eyes started scrambling the letters half way through. -Roberto -- +----| http://fslc.usu.edu/ USU Free Software & GNU/Linux Club |------+ Roberto Mello - Computer Science, USU - http://www.brasileiro.net/ http://www.sdl.usu.edu/ - Space Dynamics Lab, Developer "Data! I thought you were dead!" "No, Sir. I rebooted."