There are multiple ways to do this;
1. For each table summarize per month how much each ID was used, basically calculate the summary statistic for each month. Name each column the month plus some identifier for the stat.
2. Left join these tables together using the First table as the LEFT table to keep only ID's from that table. The Summary stats become columns months.
3. Use an Array and a a data step to identify the last month.
Pros: Step by step easy to do each step
Cons: repetitive as you're doing the same thing multiple times for different tables. You could reduce this with macros but being a beginner you should start with manual code first.
A more SAS method:
1. Create a view that appends all tables together
2. Summarize the view into the summary stats per month
3. Filter for only ID's in the first table
4. Calculate the stats needed (last month) and number of query's
Pros: Code is simpler to run
Cons: With larger data sets this is harder to test if you're not already familiar with SAS coding.
FYI - if you present data as images we'd have to type that out to type out a solution. If you cannot present actual data in a data step, including fake data as a table is preferable. Generic questions without data will get generic answers without code typically.
... View more