PostgreSQL: Query has no destination for result data

问题

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

回答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.

回答2:

Answer from SL2 was right, but you can write it in the short way:

CREATE OR REPLACE FUNCTION fun() RETURNS text AS $$
BEGIN
    --- ....
    RETURN(SELECT dblink_disconnect());
END
$$ LANGUAGE plpgsql;

回答3:

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

来源：https://stackoverflow.com/questions/23946735/postgresql-query-has-no-destination-for-result-data

标签

postgresql

common-table-expression

dblink