In the table there's a datetime column.

The following syntax converts this to two char columns, and it works fine, and it's fast.

SELECT DISTINCT TOP 100 PERCENT Member_Id,
   RTRIM(CAST(DATEPART(yyyy, [Interval]) AS char))
   + '.' + RTRIM(CAST(DATEPART(mm, [Interval]) AS char))
   + '.' + RTRIM(CAST(DATEPART(dd, [Interval]) AS char)) AS Dates,
   RTRIM(CAST(DATEPART(hh, [Interval]) AS char))
   + '.' + RTRIM(CAST(DATEPART(mi,[Interval]) AS char))
   + '.' + RTRIM(CAST(DATEPART(ss, [Interval]) AS char)) AS Times
FROM dbo.Detail