Merge datasets few to many merge

[hlg23]

I think I need to complete a few to many merge. For visual purposes, I took a screenshot of the data I want to merge on two datasets, but in reality, the data is all in one Excel file, on two different tabs. Is it possible to do a proc sql procedure to merge and combine datasets on multiple variables? I need to merge the data on "siteid" AND "date" and "rater". I have 28 sites total and each site was observed 5 times (mostly by the same "rater", but sometimes a different one), with individual observations varying by day from as few as 1 to as many as 100+. I eventually want to get an average of the "sec" variables for each site observed. ("sec" is time, in seconds, spent performing observed activity). 

Here is some code I came up with, but I have not had a chance to run it to see if it would work : 

proc sql; 

create table <want> as

select * from <have>

group by siteid

having date=min(date)

order by siteid, date, rater;

quit;

[PeterClemmensen]

Can you provide us with an example of what your desired result looks like? It is much easier to help you then.