CREATE OR REPLACE FUNCTION mostrar_media_salarios_funcionarios()
RETURNS SETOF numeric as $$
BEGIN
    RETURN QUERY
    SELECT
        AVG(C.salariocargo)
    FROM
    	tabelafuncionario as F

    INNER JOIN tabelafuncionariocargo as FC
    	ON FC.fkcpffuncionario = F.pkcpffuncionario

    INNER JOIN tabelacargo as C
    	ON C.pkcodigocargo = FC.fkcodigocargo;

END $$ LANGUAGE plpgsql;