Thread: Multiple SRF parameters from query
Hi All,
i'm having troubles trying to write a sql query using a Set Returning
Function.
I have a function foo (ID varchar) that returns a variable number of
records.
I have also a table (called Anagrafica) that contains a list of IDs to
be passed to the function foo.
As an example, just say that Anagrafica is like this:
Anagrafica
ID | n
----+---
aaa | 1
bbb | 5
ccc | 9
ddd | 10
eee | 11
and foo returns this values
select * from foo ('aaa')
a | b | c
--+---+---
1 | 2 | 3
5 | 9 | 1
select * from foo ('bbb')
a | b | c
--+---+---
4 | 0 | 0
2 | 0 | 0
0 | 0 | 0
what i would like to do is write an SQL query that looks something like
this (written in simplyfied-pseudo-sql)
SELECT FROM anagrafica WHERE n < 5 SELECT * FROM Foo (anagrafica.ID)
and that gives as result a table that is the union of foo ('aaa') and
foo ('bbb')
a | b | c
--+---+---
1 | 2 | 3
5 | 9 | 1
4 | 0 | 0
2 | 0 | 0
0 | 0 | 0
I'm having success if foo returns only a row, but the problem is that
foo returns more than one.
I think i sould use a join but i couldn't find the right syntax for it.
I don't want to create a spefic PL/pgSQL function becase i need to have
freedom in selecting IDs from Anagrafica (the one i provided is just an
example, the real table is much more complex).
I would really appreciate any suggestion.
Best regards, Federico.
On Wed, 2005-06-01 at 10:29 +0530, Ramakrishnan Muralidharan wrote:
> Hi,
>
> I am not able to understand "Returning only one row", since 'aaa' having 2 rows and 'bbb' having 3 rows and what
criteriasingle row should be returned. Please let me know the expected result and I will try to find out a solution for
it.
Sorry, it was not clear from my message.
I meant that I had success creating a table as a result of multiple
invocation of foo (parameter) using the result of an "outer" query as
list of parameter to foo, only if foo () is a "normal" function,
returning a simple value.
It was a misleading sentence anyway, since what i'm asking help for is
the case where foo () is a SRF and returns more than 1 row.
What i'm trying to do is a query where i get a result of this kind
a | b | c
--+---+---
1 | 2 | 3
5 | 9 | 1
4 | 0 | 0
2 | 0 | 0
0 | 0 | 0
given that i select from the table Anagrafica the fields 'aaa' and
'bbb', where the first 2 rows obtained as the result of foo ('aaa') and
the latter 3 as the result of foo ('bbb').
Thanks a lot for help !
PS: Sorry for late answering, i had problems with mail.
Regards,Federico.
On Sat, Jun 04, 2005 at 06:19:35PM +0200, Federico Pedemonte wrote:
>
> What i'm trying to do is a query where i get a result of this kind
>
> a | b | c
> --+---+---
> 1 | 2 | 3
> 5 | 9 | 1
> 4 | 0 | 0
> 2 | 0 | 0
> 0 | 0 | 0
>
> given that i select from the table Anagrafica the fields 'aaa' and
> 'bbb', where the first 2 rows obtained as the result of foo ('aaa') and
> the latter 3 as the result of foo ('bbb').
If you don't mind using a deprecated feature that might be removed
from future versions of PostgreSQL, then see "SQL Functions Returning
Sets" in the documentation:
http://www.postgresql.org/docs/8.0/static/xfunc-sql.html#AEN29555
To use the deprecated feature, you could wrap a complex PL/pgSQL
SRF inside a simple SQL SRF. The following example works for me
in 8.0.3:
CREATE TABLE anagrafica ( id text PRIMARY KEY, n integer NOT NULL
);
INSERT INTO anagrafica (id, n) VALUES ('aaa', 1);
INSERT INTO anagrafica (id, n) VALUES ('bbb', 5);
INSERT INTO anagrafica (id, n) VALUES ('ccc', 9);
INSERT INTO anagrafica (id, n) VALUES ('ddd', 10);
INSERT INTO anagrafica (id, n) VALUES ('eee', 11);
CREATE TYPE footype AS ( a integer, b integer, c integer
);
CREATE FUNCTION foo(id text) RETURNS SETOF footype AS $$
DECLARE rec footype;
BEGIN IF id = 'aaa' THEN rec.a := 1; rec.b := 2; rec.c := 3; RETURN NEXT rec; rec.a := 5; rec.b := 9;
rec.c:= 1; RETURN NEXT rec; RETURN; ELSIF id = 'bbb' THEN rec.a := 4; rec.b := 0; rec.c := 0; RETURN NEXT
rec; rec.a := 2; rec.b := 0; rec.c := 0; RETURN NEXT rec; rec.a := 0; rec.b := 0; rec.c := 0; RETURN NEXT
rec; RETURN; ELSE rec.a := -1; rec.b := -2; rec.c := -3; RETURN NEXT rec; RETURN; END IF;
END;
$$ LANGUAGE plpgsql STABLE STRICT;
CREATE FUNCTION bar(text) RETURNS SETOF footype AS $$
SELECT * FROM foo($1);
$$ LANGUAGE sql STABLE STRICT;
SELECT (bar(id)).* FROM anagrafica WHERE n <= 5;a | b | c
---+---+---1 | 2 | 35 | 9 | 14 | 0 | 02 | 0 | 00 | 0 | 0
(5 rows)
I don't know if there's a way to do this in a simple query without
relying on the deprecated behavior. For forward compatibility, you
might be better off writing a SRF that makes a query and loops
through the results, like this:
CREATE FUNCTION baz(query text) RETURNS SETOF footype AS $$
DECLARE rec record; retval footype;
BEGIN FOR rec IN EXECUTE query LOOP IF rec.id = 'aaa' THEN retval.a := 1; retval.b := 2; retval.c :=
3;RETURN NEXT retval; retval.a := 5; retval.b := 9; retval.c := 1; RETURN NEXT retval; ELSIF rec.id =
'bbb'THEN retval.a := 4; retval.b := 0; retval.c := 0; RETURN NEXT retval; retval.a := 2; retval.b
:=0; retval.c := 0; RETURN NEXT retval; retval.a := 0; retval.b := 0; retval.c := 0; RETURN NEXT retval;
ELSE retval.a := -1; retval.b := -2; retval.c := -3; RETURN NEXT retval; END IF; END LOOP;
RETURN;
END;
$$ LANGUAGE plpgsql STABLE STRICT;
SELECT * FROM baz('SELECT * FROM anagrafica WHERE n <= 5');a | b | c
---+---+---1 | 2 | 35 | 9 | 14 | 0 | 02 | 0 | 00 | 0 | 0
(5 rows)
Maybe somebody else can suggest improvements or alternatives.
--
Michael Fuhr
http://www.fuhr.org/~mfuhr/
Hi, I am not able to understand "Returning only one row", since 'aaa' having 2 rows and 'bbb' having 3 rows and what criteriasingle row should be returned. Please let me know the expected result and I will try to find out a solution for it. for set returning function the following link maybe helpful http://techdocs.postgresql.org/guides/SetReturningFunctions Regards, R.Muralidharan -----Original Message----- From: pgsql-sql-owner@postgresql.org [mailto:pgsql-sql-owner@postgresql.org]On Behalf Of Federico Pedemonte Sent: Tuesday, May 31, 2005 8:23 PM To: pgsql-sql@postgresql.org Subject: [SQL] Multiple SRF parameters from query Hi All, i'm having troubles trying to write a sql query using a Set Returning Function. I have a function foo (ID varchar) that returns a variable number of records. I have also a table (called Anagrafica) that contains a list of IDs to be passed to the function foo. As an example, just say that Anagrafica is like this: Anagrafica ID | n ----+--- aaa | 1 bbb | 5 ccc | 9 ddd | 10 eee | 11 and foo returns this values select * from foo ('aaa') a | b | c --+---+--- 1 | 2 | 3 5 | 9 | 1 select * from foo ('bbb') a | b | c --+---+--- 4 | 0 | 0 2 | 0 | 0 0 | 0 | 0 what i would like to do is write an SQL query that looks something like this (written in simplyfied-pseudo-sql) SELECT FROM anagrafica WHERE n < 5 SELECT * FROM Foo (anagrafica.ID) and that gives as result a table that is the union of foo ('aaa') and foo ('bbb') a | b | c --+---+--- 1 | 2 | 3 5 | 9 | 1 4 | 0 | 0 2 | 0 | 0 0 | 0 | 0 I'm having success if foo returns only a row, but the problem is that foo returns more than one. I think i sould use a join but i couldn't find the right syntax for it. I don't want to create a spefic PL/pgSQL function becase i need to have freedom in selecting IDs from Anagrafica (the one i provided is just an example, the real table is much more complex). I would really appreciate any suggestion. Best regards, Federico. ---------------------------(end of broadcast)--------------------------- TIP 1: subscribe and unsubscribe commands go to majordomo@postgresql.org