If you are still seeing multiple values it is possible you have another field that is causing each value to display rather than just displaying one entry for each unique date.
Everyone above is quite right that using the floor function to remove the time portion will truncate the timestamp leaving just the date element. In fact if you format this as a timestamp you would get e.g. 23/10/2014 00:00:00 as there is no time element left after the floor function has been used.
If there is another field in your table that has a different value against each of the identical truncated dates then this will cause more than one of the date values to show in your table.
By example, a simple script of:
Load * inline
left join (Example)
Timestamp(Date,'DD/MM/YYYY hh:mm:ss') as FormattedTimestamp,
Timestamp(Floor(Date),'DD/MM/YYYY hh:mm:ss') as FlooredTimestamp,
Date(Floor(Date),'DD/MM/YYYY') as TruncatedDate
will generate a few dates to play with.
You will see that the ID field is unique for each date but there are some dates where the date is the same but the time is different.
Dropping these fields into a table will result in:
You can see here how the floor function has removed the time element and then by formatting the floored result as a date in DD/MM/YYYY format you get the date result you want. However, you will also see that some of the dates are present more than once in the right most column. This is because the ID field is unique to the dates and as the ID field is included in the table then each related occurrence of the date will be displayed. To prevent the multiple dates from showing up you would need to remove the unique fields. So by removing the ID and formatted timestamp fields the result is:
and the multiple values have gone.
Not sure if this helps but hopefully it will.