Postgresql return text variable value - postgresql

Question

I created a function. Firstly I declared a variable When a result return I want to return variable result but I get an error. How can I solve?
Error
ERROR: column "exist-user" does not exist
CREATE OR REPLACE FUNCTION savepromotionadmin(
IN p_first_name character varying,
IN p_last_name character varying,
IN p_gsm character varying,
IN p_email character varying,
IN p_password character varying,
IN p_level smallint)
RETURNS text AS
$BODY$
DECLARE
result text;
p_user_id bigint=(select id from user where email=p_email and gsm=p_gsm);
p_check_user bigint=(select id from promotion_admin where email=p_email and gsm=p_gsm);
BEGIN
IF p_user_id is not null THEN
IF p_check_user is null THEN
insert into promotion_admin(user_id, first_name, last_name, gsm, email, level, password)
values(p_user_id, p_first_name, p_last_name, p_gsm, p_email, p_level, md5(p_password));
IF found THEN
result:="added";
return result;
ELSE
result:="error";
return result;
END IF;
ELSE
result:="exist-user";
return result;
END IF;
ELSE
result:="error";
return result;
END IF;
END;
$BODY$
LANGUAGE plpgsql VOLATILE
COST 1000;

Answer 1

When you assign a data to a variable, you use the quote literal sign '. The quote indent sign " is for specify name of database object such as database name, table name, column name.
So, the code result:="exist-user" will assign data of column exist-user to variable result, and of course that column is not exists.
You can read more here

Answer 2

The " are only for object-names (tables, columns etc.), for text you have to use '
change result:="added"; to result:='added'; and everything is fine