[GENERAL] How use input parameter as path to COPY in function?

[Bill Todd]

I am missing something basic. How can I use an input parameter as the
destination path in a COPY statement in a function. The following fails
with a syntax error at or near the parameter.

CREATE OR REPLACE FUNCTION dvd.export_tables(IN export_path text)
RETURNS void
AS
$$
BEGIN
copy dvd.genre to export_path
with
delimiter as E'\t'
null as '';
END;
$$
LANGUAGE 'plpgsql' VOLATILE

--
Sent via pgsql-general mailing list (pgsql-...@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-general

[Tom Lane]

Bill Todd <p...@dbginc.com> writes:
> I am missing something basic. How can I use an input parameter as the
> destination path in a COPY statement in a function.

plpgsql can only substitute parameter values into places where a data
value is called for in a DML statement (ie, SELECT/INSERT/UPDATE/DELETE).
To use a parameter in other contexts, such as a utility statement like
COPY, you need to construct the command as a string and EXECUTE it.
Try something like

EXECUTE 'copy dvd.genre to ' || quote_literal(export_path) ||
$q$

with
delimiter as E'\t'
null as ''

$q$ ;

(There's any number of ways to do the quoting here, of course,
but I do strongly recommend using quote_literal() on the parameter.)

regards, tom lane

[Bill Todd]

Thanks Tom. As usual, I learned a lot more from your reply than just the answer to my question .

Bill