The difference is when you have any triggers defined on the table for delete, insert or update.

Hi.

It's exactly what they describe:

• Use Delete then Insert: When updating a row it will first delete it and then re-insert it. This means that if you are using identity or autonumbers you will probably end up with a new value. Also, if there are any insert - delete triggers they will be executed!
• Use Update: An update statement will be issued. Update trigger will be executed.

Andreas.

to be clear, that option is only relevant if the primary key values are being changed (what the datawindow has set for unique key columns, not necessarily the primary key).  In other words, if you are not updating what was set for a key column then it will just be an update regardless of the setting used.