/**
 * Creates a function to checks a string variable for being either, NULL or ''.
 *
 * @author: "Stefanie Janine Stölting"<stefanie@proopensource.eu>
 * @license: PostgreSQL https://opensource.org/licenses/postgresql
 */

CREATE OR REPLACE FUNCTION is_empty(s text) RETURNS BOOLEAN AS $f1$
BEGIN
        RETURN COALESCE(s, '') = '';
END;
$f1$
LANGUAGE plpgsql IMMUTABLE
;

COMMENT ON FUNCTION is_empty(s text) IS 'Checks, whether the given parameter is NULL or ''''';