SELECT Int(([[COLOR=red]DateFieldName[/COLOR]]-DMin("[COLOR=red]DateFieldName[/COLOR]","[COLOR=red]TableName[/COLOR]"))/60) AS DateGroup
FROM [COLOR=red]TableName
[/COLOR]GROUP BY Int(([[COLOR=#ff0000]DateFieldName[/COLOR]]-DMin("[COLOR=#ff0000]DateFieldName[/COLOR]","[COLOR=#ff0000]TableName[/COLOR]"))/60);