SET @minimo = (SELECT min(data_entrata) FROM test);
SET @incrementa = 1;
SELECT
data_entrata,
IF(data_entrata < ADDDATE(@minimo, INTERVAL 70 MINUTE),
@incrementa,
@incrementa := @incrementa + 1) AS yy,
IF(data_entrata < ADDDATE(@minimo, INTERVAL 70 MINUTE),
@minimo,
@minimo := data_entrata) AS XX
FROM
test
ORDER BY data_entrata;
SELECT @incrementa as risultato;