I would like to compare last month's data with this month's data in one report

Hello. I am using FortiAnalyzer 6.0. I would like to use a macro to display the data of this month and a macro to display the data of the last month in one report. For this reason, I think that it is necessary to specify the data of the last month by editing the data set, but I do not know the method.

For example, do I need to modify the following queries if I want to display the CPU average utilization data of last month? In that case, please tell me which part will be modified.

select hourstamp, cast(sum(cpu_usage)/sum(num) as decimal(6,2)) as cpu_avg_usage from ###(select $hour_of_day as hourstamp, sum(cpu) as cpu_usage, count(*) as num from $log where $filter and subtype='system' and action='perf-stats' group by hourstamp)### t group by hourstamp order by hourstamp

Or should I set it with Variables? In that case, please tell me how to set Variables. I do not know how to extract last month's data with dataset.

Please help me.

best regards.