This is in the planning stage and doesn't involve SQL. Perhaps I should have said read/write operations on a text file instead. Apologies.

The file would look something like this, where the first column is an id column which would be used when updating or removing the relevant record from the file

id col1 col2 col3 col4 username email.address status
[download]

I'd envisage around 3000 records being present in the file to start with. Growing over time to a much larger number (50,000 records). So performance will play a part as the file grows.