CREATE FUNCTION public.addupdateemployee(IN employeeid bigint, IN employeetitle text, IN employeeaddress text)
RETURNS bigint
LANGUAGE 'plpgsql'

AS $BODY$
BEGIN
DECLARE affectedrecordid bigint = 0
IF employeeid = 0 THEN
INSERT INTO employeemaster(title, address)
values(employeetitle, employeeaddress)
RETURNING id INTO affectedrecordid;
RETURN affectedrecordid;
ELSE
UPDATE employeemaster
SET title = employeetitle,
address = employeeaddress
WHERE id = employeeid
RETURN employeeid;
END IF
END
$BODY$;

ERROR:  syntax error at or near "IF"
LINE 8: IF employeeid = 0 THEN
        ^
SQL state: 42601
Character: 218