SELECT T1.*
FROM T1
WHERE NOT EXISTS(SELECT NULL
FROM T2
WHERE T1.ID = T2.ID
AND T1.Date = T2.Date
AND T1.Hour = T2.Hour)
It could also be done with a LEFT JOIN
:
SELECT T1.*
FROM T1
LEFT JOIN T2
ON T1.ID = T2.ID
AND T1.Date = T2.Date
AND T1.Hour = T2.Hour
WHERE T2.ID IS NULL