Hello, i am very new to java programming and i am not sure it this is the right forum to post my question. Pardon me if i post it at the wrong forum. I am now working on a project that requires me to use netbeans, glassfish, javadb to create a jsp file.

I have build a table in the jsp file which display the database values which allows the user to add and delete values by using textboxes and values will be updated to the database.

For example right now the table contains an id 3 however when i try delete it, i am able to but when i would want to add back the id 3 i am unable to. why is this so?

And how can i compare the values of the textboxes with the table to check if the values keyed in textboxes does not appears in the table twice?

Needing urgent help, hope to hear form you all soon.