DROP FUNCTION IF EXISTS CalcularDuracaoMediaEstadias;
    DELIMITER $$
    CREATE FUNCTION CalcularDuracaoMediaEstadias()
    RETURNS INT DETERMINISTIC
    BEGIN
        DECLARE duracaoMedia INT;
        SELECT ROUND(AVG(DATEDIFF(data_fim, data_inicio)))
        INTO duracaoMedia
        FROM alugueis;
        RETURN duracaoMedia;
    END$$
    DELIMITER ;
    SELECT CalcularDuracaoMediaEstadias() AS MediaEstadia;