I have the following procedure:
DROP FUNCTION presAdress();
CREATE FUNCTION presadress() RETURNS VARCHAR(100) AS $$
DECLARE studioName text;
BEGIN
RETURN (
SELECT address AS pres_address
FROM MovieExec
WHERE cert# IN (
SELECT presC#
FROM Studio
WHERE name = studioName)
);
END;
$$ LANGUAGE plpgsql;
I try to run the procedure:
select presadress('Paramount');
But I get the following error message:
ERROR: function presadress(text) does not exist
SQL state: 42883
Hint: No function matches the given name and argument types. You might need to add explicit type casts.
Character: 294
I suspect that this is because there is some kind of error regarding the in parameters of the procedure, but I have been unable to find a solution.
Use a function parameter, like #Gordon demonstrates, but you don't need plpgsql for this at all. And the query can simplified (shorter, faster):
CREATE FUNCTION presadress(_studioname text)
RETURNS text AS
$$
SELECT m.address
FROM studio s
JOIN movieexec m ON m.cert# = s.presc#
WHERE s.name = _studioname
$$ LANGUAGE sql STABLE;
Function volatility can be STABLE.
Related:
How do IMMUTABLE, STABLE and VOLATILE keywords effect behaviour of function?
Difference between language sql and language plpgsql in PostgreSQL functions
PostgreSQL Stored Procedure Performance
I think you want a declaration more like this:
CREATE FUNCTION presadress (v_studioName text)
RETURNS VARCHAR(100) AS $$
BEGIN
RETURN(SELECT address AS pres_address
FROM MovieExec
WHERE cert# IN (SELECT presC#
FROM Studio
WHERE name = v_studioName)
);
END;
$$ LANGUAGE plpgsql;
Related
This function works:
CREATE OR REPLACE FUNCTION public.a()
RETURNS TABLE(a text)
LANGUAGE plpgsql
AS $function$
BEGIN
return query execute
'select a from ztable';
END;
$function$;
But when I try to add some text to the column name:
CREATE OR REPLACE FUNCTION public.a(prefix text)
RETURNS TABLE(a text)
LANGUAGE plpgsql
AS $function$
BEGIN
return query execute
'select a as $1_a from ztable' using prefix;
END;
$function$;
This just fails as a syntax error on $1.
Or:
CREATE OR REPLACE FUNCTION public.a(prefix text)
RETURNS TABLE(a text)
LANGUAGE plpgsql
AS $function$
BEGIN
return query execute
'select a as '||prefix||'_a from ztable';
END;
$function$;
select * from a('some prefix') doesn't work.
Is there some other syntax that does the job?
That's simply not possible. SQL does not allow dynamic column names.
You must assign a column alias with the call. Like:
SELECT a AS prefix_a FROM public.a();
Or in a column definition list directly attached to the function:
SELECT * FROM public.a() AS f(prefix_a);
Or, while dealing with a single output column, even just:
SELECT * FROM public.a() AS prefix_a;
See:
RETURNING rows using unnest()?
Postgresql 12. Want a function to return query by calling another function but don't know how to call.
create or replace function getFromA()
returns table(_id bigint, _name varchar) as $$
begin
RETURN QUERY SELECT id, name from groups;
end; $$ language plpgsql;
create or replace function getFromB()
returns table(_id bigint, _name varchar) as $$
begin
return query select getFromA();
end; $$ language plpgsql;
select getFromB();
gets error:
SQL Error [42804]: ERROR: structure of query does not match function result type
Detail: Returned type record does not match expected type bigint in column 1.
Where: PL/pgSQL function getfromb() line 3 at RETURN QUERY
How to fix this?
The problem is in getFromB():
return query select getFromA();
Unlike some other databases, Postgres allows set-returning functions directly in the select clause. This works, but can be tricky: this returns a set, hence not the expected structure.
You would need to select ... from getFromA() instead: this way it returns the proper data structure.
create or replace function getFromB()
returns table(_id bigint, _name varchar) as $$
begin
return query select * from getFromA();
end; $$ language plpgsql;
Demo on DB Fiddle
I want to return a row from a table with this function (I don't know the name of the table, it's random)
CREATE FUNCTION foo( text ) RETURNS setof record AS $$
DECLARE
table_name ALIAS FOR $1;
BEGIN
SELECT * from table_name ;
END
$$ LANGUAGE plpgsql;
and then I want to do this:
select col1,col2 from foo('bar');
Any ideas?
SQL demands to know the return type at call time. And functions require you to define a return type as well. What you are after is not trivial.
If you don't know the return type at call time, you are basically out of luck. You cannot solve the problem with a single function call.
If you know the type at call time, there is an option with polymorphic types and dynamic SQL with EXECUTE:
CREATE OR REPLACE FUNCTION f_data_of_table(_tbl_type anyelement)
RETURNS SETOF anyelement AS
$func$
BEGIN
RETURN QUERY EXECUTE
'SELECT * FROM ' || pg_typeof(_tbl_type);
END
$func$ LANGUAGE plpgsql;
Call:
SELECT * FROM f_data_of_table(NULL::my_table_name);
Details in this related answer:
Refactor a PL/pgSQL function to return the output of various SELECT queries
Be wary of SQL injection:
Table name as a PostgreSQL function parameter
Only makes sense if you do more than just SELECT * FROM tbl, or you'd simply use the SQL command.
Aside:
Do not use ALIAS to attach names to parameter values. That's outdated and discouraged. Use named parameters instead.
I am trying to create a function that returns a SELECTed resultset.
When I call my postgres function like this select * from tst_dates_func() I get an error as shown below:
ERROR: query has no destination for result data
HINT: If you want to discard the results of a SELECT, use PERFORM instead.
CONTEXT: PL/pgSQL function "tst_dates_func" line 3 at SQL statement
********** Error **********
ERROR: query has no destination for result data
SQL state: 42601
Hint: If you want to discard the results of a SELECT, use PERFORM instead.
Context: PL/pgSQL function "tst_dates_func" line 3 at SQL statement
Here is the function I created:
CREATE OR REPLACE FUNCTION tst_dates_func()
RETURNS TABLE( date_value date, date_id int, date_desc varchar) as
$BODY$
BEGIN
select a.date_value, a.date_id, a.date_desc from dates_tbl a;
END;
$BODY$
LANGUAGE plpgsql;
I am not sure why I am getting the above error. I would like to run select * from tst_dates_func();
and get data back. Or further join the result set if needed. What is the problem here?
Do it as plain SQL
CREATE OR REPLACE FUNCTION tst_dates_func()
RETURNS TABLE( date_value date, date_id int, date_desc varchar) as
$BODY$
select a.date_value, a.date_id, a.date_desc from dates_tbl a;
$BODY$
LANGUAGE sql;
If you really need plpgsql use return query
CREATE OR REPLACE FUNCTION tst_dates_func()
RETURNS TABLE( date_value date, date_id int, date_desc varchar) as
$BODY$
BEGIN
perform SELECT dblink_connect('remote_db');
return query
select a.date_value, a.date_id, a.date_desc from dates_tbl a;
END;
$BODY$
LANGUAGE plpgsql;
In PLPGSQL - use RETURN QUERY
CREATE OR REPLACE FUNCTION tst_dates_func()
RETURNS TABLE( date_value date, date_id int, date_desc varchar) as
$BODY$
BEGIN
RETURN QUERY (select a.date_value, a.date_id, a.date_desc from dates_tbl a);
END;
$BODY$
LANGUAGE plpgsql;
I couldn't do it as plain SQL as I needed to enter some data into a database for further processing and wanted to create a variable. Or at least I did not figure out the correct syntax for that. And the accepted answer had code I did not need, such as connecting to the database, as I ran this from inside pgAdmin with a connection setup already. I also had to drop the function when I made edits to it.
I was using this for inserting a geometry for intersection. A different use case and example could help someone else. This also shows how to then view this data and use it just like a table.
-- Get a geojson shape inside of postgres for further use
DROP FUNCTION fun();
CREATE OR REPLACE FUNCTION fun()
RETURNS TABLE (geometry geometry) AS
$BODY$
DECLARE geojson TEXT;
BEGIN
geojson := '{
"type":"Polygon",
"coordinates":[[[-90.9516399548092,39.8942337977775],[-90.9513913202472,39.8936939306154],[-90.9522805177147,39.8937108246505],[-90.9549542293894,39.8937616571416],[-90.954948768846,39.8945506794343],[-90.9531755591848,39.894492766522],[-90.9531770788457,39.8942868819087],[-90.9516399548092,39.8942337977775]]],
"crs":{"type":"name","properties":{"name":"EPSG:4326"}},
}';
return query (SELECT ST_GeomFromGeoJSON(geojson) AS geometry);
END;
$BODY$
LANGUAGE plpgsql;
-- View test insert
SELECT * FROM fun()
I have a Postgresql function in which there is only a SELECT statement:
CREATE OR REPLACE FUNCTION fun_test()
RETURNS INTEGER AS $$
DECLARE size INTEGER;
BEGIN
SELECT COUNT(*) INTO size FROM tab;
RETURN size;
END;
$$ LANGUAGE plpgsql STABLE;
When I call the function with:
SELECT fun_test()
Although the result are correct, there will be a warning too:
WARNING: A stable or volatile function is used as if it is immutable
HINT: The function should be declared as stable or volatile in create function statement.
I found in Postgresql document that STABLE is a appropriate selection for functions whose results depend on database lookups, parameter variables (such as the current time zone), etc. http://www.postgresql.org/docs/8.2/static/sql-createfunction.html
My question is where the warning comes from? It seems that I am doing what the document requires to do. Any help is appreciated.
EDIT:
I am using postgresql server 8.2.15
The whole story:
CREATE TABLE algo.chengb_tmp
(
userid INT,
username varchar(100)
)
CREATE OR REPLACE FUNCTION algo.chengb_fun_test()
RETURNS INTEGER AS $$
DECLARE size INTEGER;
BEGIN
SELECT COUNT(*) INTO size FROM algo.chengb_tmp;
RETURN size;
END;
$$ LANGUAGE plpgsql STABLE;
SELECT algo.chengb_fun_test()
cheng
Obviously, your question does not show the whole story. I tested your function in PostgreSQL 9.1 and it works for me, as expected. No warning.
Possible explanations include:
A RULE on SELECT on the involved table tab that calls another function. (There are no triggers for SELECT)
A bug in the outdated PostgreSQL version 8.2.15, which might go away with an upgrade.
You over-simplified the question and abstracted the actual cause of the problem away.
Add more details in the question: your Version of PostgreSQL, the complete definition of table tab, the complete error message and its context.
As an aside, could be simplified:
CREATE OR REPLACE FUNCTION fun_test()
RETURNS INTEGER AS
$$
BEGIN
RETURN
(SELECT COUNT(*) FROM tab);
END;
$$ LANGUAGE plpgsql STABLE;
Ore even:
CREATE OR REPLACE FUNCTION fun_test()
RETURNS INTEGER AS
$$
SELECT count(*) FROM tab;
$$ LANGUAGE sql STABLE;
But that's probably not the point here.