Re: Getting results from a dynamic query in PL/pgSQL
От | Patrick Fiche |
---|---|
Тема | Re: Getting results from a dynamic query in PL/pgSQL |
Дата | |
Msg-id | 85058ADF852DD5118FD50002A528A5B6079B52@SERVEUR обсуждение исходный текст |
Ответ на | Getting results from a dynamic query in PL/pgSQL (johann.uhrmann@xpecto.com (Johann Uhrmann)) |
Ответы |
Re: Getting results from a dynamic query in PL/pgSQL
(Johann Uhrmann <johann.uhrmann@xpecto.com>)
|
Список | pgsql-general |
I'm not sure I really understood what you want... Here is perhaps what you need... CREATE TABLE t1 ( col1 text ); create or replace function foo(text) returns text as ' DECLARE colname ALIAS FOR $1; sqlquery text; result text; BEGIN sqlquery := ''INSERT INTO t1 (col1 ) SELECT '' || colname || '' from toto''; EXECUTE( sqlquery ); SELECT INTO result col1 FROM t1; DELETE FROM t1; RETURN result; END; ' language 'plpgsql'; ---------------------------------------------------------------------------- --------------- Patrick Fiche email : patrick.fiche@aqsacom.com tél : 01 69 29 36 18 ---------------------------------------------------------------------------- --------------- -----Original Message----- From: pgsql-general-owner@postgresql.org [mailto:pgsql-general-owner@postgresql.org]On Behalf Of Johann Uhrmann Sent: Monday, January 27, 2003 4:02 PM To: pgsql-general@postgresql.org Subject: [GENERAL] Getting results from a dynamic query in PL/pgSQL Hello, is there a possibility to retrieve results from a dynamically generated query in PL/pgSQL? That would be like this: create function foo(text) returns text as ' DECLARE colname ALIAS FOR $1; result text; BEGIN SELECT INTO result colname from my_table; RETURN result; END; ' language 'plpgsql'; The actual column that is to be read from my_table should be passed as argument to the function. The example does not read the variable colname but tries to read a column named "colname" from my_table which is not how it should work. The keyword "EXECUTE" which could execute dynamic queries cannot return any value that a select statement would. (At least there is nothing about that in the docs.) In order to write a trigger function that reads column names out of a table and uses those column names afterwards, I need such a functionality. I tried a workaround by using EXECUTE to create a function that reads only the columns I need and then calling this dynamically generated function. However, that works only one time - then I get the following message: ERROR: plpgsql: cache lookup for proc 52118 failed plpgsql seems to cache the dynamically generated function even after it gets dropped or overwritten with "create or replace function...". Does anyone know how to use column names stored in variables within PL/pgSQL? Thank You in advance, Johann Uhrmann ---------------------------(end of broadcast)--------------------------- TIP 3: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to majordomo@postgresql.org so that your message can get through to the mailing list cleanly
В списке pgsql-general по дате отправления:
Предыдущее
От: "Shridhar DaithankarДата:
Сообщение: Re: Using RSYNC for replication?