Grouping data on a date-and-time column
When you group data on a date-and-time column, you have two options. You can show every individual date or time value, or you can group the data by a specific time interval, which is the typical option. You can organize a shipping report, for example, showing shipment data by month or by quarter, rather than by date.
Figure 5-10 shows three reports that contain the same data.
Figure 5-10  
The report on the left displays data that has not been grouped, the second report groups shipment dates using individual date values, and the third report groups shipment dates by month.

Additional Links:

Copyright Actuate Corporation 2012