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. The second option is more typical. A shipping report, for example, can organize shipment data by month or by quarter, rather than by date.

Figure 4‑9 shows three report designs that contain the same data. The first report design displays data that has not been grouped, the second design groups shipment dates using individual date values, and the third design groups shipment dates by month.