Avoiding duplicate entries into a table

hi,Im using an Actionlistener to get a Button to insert a certain value into a database. However, when I press on the button twice in a row, it enters the same exact data into two seperate entries.Does anyone know how to avoid this?Thanks
[266 byte] By [Bakumba84a] at [2007-10-2 17:44:57]
# 1
Yes. I call it a primary key. Good stuff that.
Bakumba84a at 2007-7-13 19:02:42 > top of Java-index,Database Connectivity,Java Database Connectivity (JDBC)...