count rows in one table that is related to another table

 I have a systems table which contains a "systemtype" , "narserno".  also I have a luns table which has "narserno" and luninfo field. 

for each systemtype, I want to count total in the systems table where luninfo in the luns table contains a key work of "oracle".  

I have this query, but it doesnt look right (too many value returns),  could you one point out where my problem is:

select systemtype, count(l.luninfostring) counts from systemconfig s, lunperformancesummary l 

where s.narserno=l.arrayid and l.luninfostring like '%oracle%' group by systemtype

order by counts desc;

Thanks,

CP