Are SQL 'tables' stored on memory or Hard-disk?

Question

Hi,
I'm designing a servlet using JDBC & SQL.
I checked-out the Java.sun JDBC turoial "Coffee table" example, and decided to use the
rs = stmt.executeUpdate("CREATE TABLE MyStuff....");
I'm looking for a temoporary storage of small amt of data (~8 rows,4 colomns) prior to updation of a REAL Database.So, The customer could easily cancel the order at ant time durring the session.
Have I chosen the wrong method to accomplish this?
Thnaks.
Regards,
Nemo

Answer 1

hello aesh83,
I think you should use the transaction commit feature
of the JDBC for this.. by turning autocommit to OFF
, you can do the transactions and then control if the
change is to be actually done in the database or can
rollback This is trickier than you think.
You absolutely do NOT want to hold a database connection from web page to web page, because there can be infinitely long delays between the pages and you'll rapidly run out of connections.
The simple way to do this (simple in theory) is to store the temporary information in the HttpSession object in memory, and when the user goes to a "commit this" URL to tell you that they want to commit the transaction, insert the whole thing into the database in one shot.
You could get much fancier, of course. You could have a database-backed cart, and some mechanism for the customer to access previously-created carts (in case their browser session dies or they move to a different computer), and some way to "commit" a cart by creating the final transaction and removing the cart. You'll also need a way (maybe) to remove old, dead carts using a periodic maintenance operation.