If you add a format such as dddd mm/dd/yyyy, it displays a date as Tuesday 05/19/2000. This may not be sufficient if you need to perform analysis on data based on the day of the week. Despite the display format, the data in the field is still a date. That is, if you need to compare sales for Mondays versus other days of the week over a given time period, changing the display format does not address your original question. In this case, you need to group all Mondays to do that sort of analysis.
To analyze data based on the day of the week:
In the Results section, select the item and choose Results, then Add Computed Item.
In the Definition field, type: to_char(<MyDate>,'dddd')
Replace <MyDate> with the name of the column for which you need the day of the week information. This creates a string from the date column with the desired format, as discussed earlier. You can also add the following:
: decode((NEXT_DAY ( <MyDate>, 'Sunday' )) -<MyDate>, 7,'Sunday', 6,'Monday', 5,'Tuesday', 4,'Wednesday', 3,'Thursday', 2,'Friday', 1,'Saturday', 'Error!')