Jeff - Destination is unknown, we just need to place file in network location in specific format requested by destination team.
There could be a serious advantage in doing this if we knew the destination. By that I mean, is it an SQL Server, an Oracle Server, a spreadsheet, or ??? You should as the destination team.
At the very least, we need to know what that "specific format" is because even that can help us help you much better.
We also need to know in no uncertain terms, what needs to be in that destination file. Is it supposed to be just differences between what you peel out of Oracle and what you are maintaining in SQL Server? In your Step 2 on the original post, it seems like you're saying that everything should be only "new members" because you state "all are new members" and yet, in Step 3, you say you have to check if they're new members or not and in Step 4, you talk about updating existing members. That's leads us to your response to Y.B. where you state "Yes - source contains all data" but we don't actually know what you mean by "all data" because of what you said in your Step 2.
So, we need to know for sure...
1. What is actually contained in the source data from the Oracle system? Is it truly ALL THE DATA with the full monty of ALL MEMBERS whether they're new or not or is it something less than that?
2. What needs to actually be in the destination file you're trying to create? Is it ONLY changes from yesterday's file (Inserts/Updates) that you received or is it something else?
3. What IS the required format for the destination file? Is it fixed width fields, true CSV with double quoted text columns, "stupid" CSV where only the text data that has commas in it gets double quoted (the double quotes are also known as text qualifiers), TAB separated, or ???
I guess my other question is why in the heck aren't you folks doing this on the system of record? In other words, the Oracle system supposedly contains "ALL of the data"... why are you good folks duplicating the Oracle data on an SQL Server to do this instead of getting the folks on the Oracle system to do it? It's been more than a decade since I've had to work with Oracle but I do remember that it was pretty easy to do such things (and I did a lot of these types of things).