How to run an ad-hoc script in PostgreSQL?

问题

I'm trying to run this in PostgreSQL 9.2:

RAISE NOTICE 'hello, world!';

And the server says:

Error : ERROR:  syntax error at or near "RAISE"
LINE 1: RAISE NOTICE 'hello, world!'
        ^

Why?

回答1:

Use an anonymous code block:

DO language plpgsql $$
BEGIN
  RAISE NOTICE 'hello, world!';
END
$$;

Variables are referenced using %:

RAISE NOTICE '%', variable_name;

回答2:

raise is PL/pgSQL only.

http://www.postgresql.org/docs/current/static/plpgsql-errors-and-messages.html

create or replace function r(error_message text) returns void as $$
begin
    raise notice '%', error_message;
end;
$$ language plpgsql;

select r('an error message');
NOTICE:  an error message

回答3:

simple example:

CREATE OR REPLACE FUNCTION test()     
RETURNS TRIGGER AS
'
DECLARE


num int;

 BEGIN
IF TG_OP = ''INSERT'' THEN
select count(*) into num from test_table;
IF num >= 1 THEN
RAISE WARNING ''Cannot Insert more than one row'';
RETURN OLD;
END IF;
ELSE
RETURN NEW;
END IF;

END;
' LANGUAGE plpgsql;

来源：https://stackoverflow.com/questions/18828127/how-to-run-an-ad-hoc-script-in-postgresql