How to chek if the username has been taken

Question

hi all,
i have a swing panel to indicate user to create his account by entering his user name, password and other data.
how can i implement the program to check if the user name has been taken
, then go back to tell user that his user name can not be taken.
otherwise, go on the store whole data entered by the user.
thanks

Answer 1

Sorry I forgot to mention speed is just not an issue
on a single record lookup.
rykk
so it means if you want to check a single record exists or not in db > for 100 times, either you will create a new database connection 100
times or you will use the connection from pool, I think both the
cases are slower than doing a lookup in hashtable. Of course it is slower. The point is it does not matter if it is slower as users will be logging on 1 at a time over a period of time. The time to establish a connection (assuming you are not using connection pooling), query for a single record and close the connection is exceptionally quick. This is assuming you have a server that is even close to adquate. The only time to worry is if your server is loaded beyond capacity and any query is degrading other user functions. In normal systems the user will be interacting with the database in all the various functions they perform - it is much more important to worry about efficency in these functions.
rykk