Convert MS SQL datetime to Oracle varchar(32) interval
As my data for LABEL_YYY_MM_DD_HH24_MI will always be the same length I can simply write:

left(convert(varchar(32),convert(smalldatetime,floor(cast(q.InTimeStart as float)*(24/.25))/(24/.25)),120),16) as LABEL_YYYY_MM_DD_HH24_MI, 


If the results were of a dynamic length and we needed to remove the last three we would need to use len(x,-3):

left(convert(varchar(32),convert(smalldatetime,floor(cast(q.InTimeStart as float)*(24/.25))/(24/.25)),120),
 len(convert(varchar(32),convert(smalldatetime,floor(cast(q.InTimeStart as float)*(24/.25))/(24/.25)),120)) -3) as LABEL_YYYY_MM_DD_HH24_MI,