PostgreSQL: Query has no destination for result data - postgresql

Question

I am trying to fetch data from remote db by using dblink through function but getting an error "query has no destination for result data". I am using plpgsql language to do the same.
Function:
CREATE OR REPLACE FUNCTION fun()
RETURNS text AS
$$
begin
select dblink_connect(
'port=5432 dbname=test user=postgres password=****');
WITH a AS (
SELECT *
FROM dblink(
'SELECT slno,fname,mname,lname
FROM remote_tbl'
) AS t (slno int, fname text, mname text, lname text)
)
, b AS (
INSERT INTO temptab1
SELECT slno, name
FROM a
)
, c AS (
INSERT INTO temptab2
SELECT slno, name
FROM a
)
INSERT INTO temptab3
SELECT slno, name
FROM a;
select dblink_disconnect();
end;
$$
LANGUAGE plpgsql;
Calling Function:
select fun();
Error: query has no destination for result data

Answer 1

The stored procedure won't just return the result of the last SELECT. You need to actually return the value:
CREATE OR REPLACE FUNCTION fun() RETURNS text AS $$
BEGIN
--- ....
RETURN(SELECT dblink_disconnect());
END
$$ LANGUAGE plpgsql;
You're getting the error because Postgres expects the function to return something of type text, but your function doesn't return anything.

Answer 2

Use a plain SQL function instead of PL/PgSQL, or use SELECT INTO and ordinary RETURN.

Answer 3

Reason for the error you're getting is because there is no return in between your BEGIN and END for example:
BEGIN
update mytable set lastcodeused = to_char(cast(lastcodeused as INTEGER)+1, 'FM999999999999999999') where
classid = classIdVar and appid= appIdInt
RETURNING concat(pageUniqueCode,lastcodeused) as pageUniqueCode
into taskcode;
return taskcode;
END;

Answer 4

If you have this error using a pgplsql procedure or function, and you are sure that the return is defined correctly, there exists a different non-intuitive cause. I needed some time to realize this so I think it is worth sharing. I had a function like this:
CREATE OR REPLACE FUNCTION "db".fn_x(
id integer)
RETURNS TABLE(b_val varchar(100), c_val varchar(100))
LANGUAGE 'plpgsql'
AS $BODY$
DECLARE
var_b_val varchar(100);
var_c_val varchar(100);
BEGIN
select var_b, var_c
-- Missing INTO clause was the cause of the error.
var_b_val, var_c_val
from "db".table_y where y_id = id;
return query(select var_b_val, var_c_val);
END;
$BODY$;
Just adding that missing INTO clause made the function work correctly.
In conclusion, this error can also trigger on silent syntax errors.