I want the found as well as the not found records hence the use of the LEFT JOIN. This happens to me once a month when a real big file comes in for a bank. They have duplicate records in them a lot of the times. They really are not dupes because they are legitimate transactions. The way I found them last year was the problem records were manually put into the table. I looked at the entries and they were all the same. This results in only one of them being left in the table after the join.

There are some cases where I don't have a match for the companyid. That's okay. I deal with that in another way.