Create user or role from inside a function?

On Fri, Sep 01, 2006 at 08:13:14PM +1000, Dan wrote:

Hey,

I am running PostgreSQL 8.1.4 and I want to create a user from inside a
function. Is this possible in 8.1?

Ive found quite a few references on google using EXECUTE, but this seems
relevant to earlier versions, not 8.1.

Does it make a difference if you use single quotes rather than double
(taking into account the need to escape then). They mean somewhat
different things...

Have a nice day,
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Dan <ml@mutox.org> schrieb:

Hey,

I am running PostgreSQL 8.1.4 and I want to create a user from inside a
function. Is this possible in 8.1?

Ive found quite a few references on google using EXECUTE, but this seems
relevant to earlier versions, not 8.1.

I have a function like this:

CREATE FUNCTION user_create (un varchar, uid bigint, pw varchar) RETURNS
VARCHAR LANGUAGE plpgsql AS '
BEGIN
EXECUTE "CREATE USER " || un || " WITH PASSWORD " || pw;

RETURN un;
END
';

This works:

CREATE or replace function user_create (un varchar, uid bigint, pw varchar) RETURNS VARCHAR AS $$
BEGIN
EXECUTE 'create user ' || un || ' with password ' || quote_literal(pw);
return $1;
end;
$$ language plpgsql;

Andreas
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On Fri, Sep 01, 2006 at 08:13:14PM +1000, Dan wrote:

I am running PostgreSQL 8.1.4 and I want to create a user from inside a
function. Is this possible in 8.1?

...

I have a function like this:

...

Executing this function yields:

# SELECT user_create('bob',1234,'bobspassword');
ERROR: column "CREATE USER " does not exist
CONTEXT: SQL statement "SELECT "CREATE USER " || $1 || " WITH PASSWORD
" || $2 "
PL/pgSQL function "user_create" line 2 at execute statement

...

Any tips would be appreciated.

http://cvs.savannah.gnu.org/viewcvs/gnumed/gnumed/server/sql/gmCreateUserFunction.sql?rev=1.5&amp;root=gnumed&amp;view=markup

This might help.

Karsten
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thanks!

I actually came to a similar solution after Roman's post.

Thanks all for the replies!

(Sending to the list as I accidently only replied to Roman with my earlier
reply)

Thanks for your assistance. This was a case of user error. To me the
examples I looked at used the double quote (") but on further inspection
they do indeed use double single quotes (').

The quote_literal function was also handy for this.

Thanks again!

Regards,

Dan

# ml@mutox.org / 2006-09-01 20:13:14 +1000:

Hey,

I am running PostgreSQL 8.1.4 and I want to create a user from inside a
function. Is this possible in 8.1?

Ive found quite a few references on google using EXECUTE, but this seems
relevant to earlier versions, not 8.1.

I have a function like this:

CREATE FUNCTION user_create (un varchar, uid bigint, pw varchar) RETURNS
VARCHAR LANGUAGE plpgsql AS '
BEGIN
EXECUTE "CREATE USER " || un || " WITH PASSWORD " || pw;

RETURN un;
END
';

Double quotes can be used only for identifiers (table, column
names, etc), you want to use single quotes for strings. Now, since
you already are in a string (the function body), you need to escape
the single quotes inside. In SQL this is done by doubling the quote
character, IOW, by putting another single quote just before it:

CREATE FUNCTION foo() ...
AS '
BEGIN
EXECUTE ''CREATE USER '' || un || '' WITH PASSWORD '' || pw;
RETURN un;
END
';

That assumes that the un and pw parameters are always passed already
quoted, otherwise you'll get errors like this:

test=# CREATE FUNCTION user_create (un varchar, uid bigint, pw varchar) RETURNS
test-# VARCHAR LANGUAGE plpgsql AS '
test'# BEGIN
test'# EXECUTE ''CREATE USER '' || un || '' WITH PASSWORD '' || pw;
test'# RETURN un;
test'# END
test'# ';
CREATE FUNCTION
test=# select user_create('fubar', 0, 'pass');
ERROR: syntax error at or near "pass" at character 33
QUERY: CREATE USER fubar WITH PASSWORD pass
CONTEXT: PL/pgSQL function "user_create" line 2 at execute statement
LINE 1: CREATE USER fubar WITH PASSWORD pass
^
test=#

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