yes, you can create temporary tables in SQL...but there is a time and a place for it. temporary databases? for get it, you'l have way too many permissions problems to even bother trying. I think you need to get a better understanding on updates and deletes instead.

you would not want to copy lacs/millions of rows to a temporary table, just to protect the original data. you simply let them SELECT data, and only UPDATE what they changed(and are ALLOWED to change)

for example, an application will select some data....that means it requests a copy of the data so it can be presented...so the presentation layer(web page, vb.net, whatever) ALREADY has a copy of the data. does it make a difference if it is a copy of a copy of the data? No.

The programmer can decide whether the data gets updated/posted back to the server or not, based on whatever rules you impose...so the question for you really is what, EXACTLY, do you want to do?