>I have a report that has one grouping data, say
>myGroup_id. It is fairly simple to define a report
>variable to count the number of records for each
>different value of myGroup_id.
>
>But, How do you define a variable that counts the
>number of distinct values myGroup_id takes at the
>end of the report?
>
>Thanks in advance,


Make a new report variable "grp_cnt" and set the following in the "Report Variables" dialog box:

initial value = 0
reset on myGroup_id change
make it a "Count" variable

This variable now will automatically be incremented by 1 within your group and be reset to 0 when the grouping variable changes.

In the report summary area, create a field whos expression is "iif(grp_cnt=1,1,0)" and make it a "Sum" calculation.

This field sums the expression "iif(grp_cnt=1,1,0)" for each record processed but since grp_cnt is a counter that's being reset for each group, it equals 1 only once per group.

So when you sum the expression, the result equals to the number of groups you have.