I have this in my code:
String query = "INSERT INTO usermail (FirstName, LastName, Town, Country, Email) " + "VALUES (?, ?, ?, ? ,?)"; My table is as follows :
UserID – AutoNumber (Primary Key) FirstName – varchar(15) astName – varchar (15) Town – varchar(15) Country – varchar(15) Email – varchar(20) The thing is that when I fill the form for the first time all the values are added into the database, but if I try to do it the second time they won't be added. If I remove the UserID table everything works perfectly. This is how I created UserID (image taken from - here)

I am unsure on how to make it work with the UserID. I cannot input anything in there since I dont have such a field in my form.
This is what I get from stackTrace
Info: visiting unvisited references Info: visiting unvisited references Info: Loading application [MailRegistration] at [/MailRegistration] Info: MailRegistration was successfully deployed in 293 milliseconds. Severe: com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Duplicate entry '1' for key 'PRIMARY' at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) at java.lang.reflect.Constructor.newInstance(Constructor.java:423) at com.mysql.jdbc.Util.handleNewInstance(Util.java:411) at com.mysql.jdbc.Util.getInstance(Util.java:386) at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1040) at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4120) at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4052) at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2503) at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2664) at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2794) at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:2155) at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2458) at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2375) at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2359) at Data.MailDB.insert(MailDB.java:32) at details.DisplayUserDetailsServlet.doPost(DisplayUserDetailsServlet.java:44) at javax.servlet.http.HttpServlet.service(HttpServlet.java:707) at javax.servlet.http.HttpServlet.service(HttpServlet.java:790) at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1682) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:318) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:160) at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:734) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:673) at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:99) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:174) at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:416) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:283) at com.sun.enterprise.v3.services.impl.ContainerMapper$HttpHandlerCallable.call(ContainerMapper.java:459) at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:167) at org.glassfish.grizzly.http.server.HttpHandler.runService(HttpHandler.java:206) at org.glassfish.grizzly.http.server.HttpHandler.doHandle(HttpHandler.java:180) at org.glassfish.grizzly.http.server.HttpServerFilter.handleRead(HttpServerFilter.java:235) at org.glassfish.grizzly.filterchain.ExecutorResolver$9.execute(ExecutorResolver.java:119) at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeFilter(DefaultFilterChain.java:283) at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeChainPart(DefaultFilterChain.java:200) at org.glassfish.grizzly.filterchain.DefaultFilterChain.execute(DefaultFilterChain.java:132) at org.glassfish.grizzly.filterchain.DefaultFilterChain.process(DefaultFilterChain.java:111) at org.glassfish.grizzly.ProcessorExecutor.execute(ProcessorExecutor.java:77) at org.glassfish.grizzly.nio.transport.TCPNIOTransport.fireIOEvent(TCPNIOTransport.java:536) at org.glassfish.grizzly.strategies.AbstractIOStrategy.fireIOEvent(AbstractIOStrategy.java:112) at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.run0(WorkerThreadIOStrategy.java:117) at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.access$100(WorkerThreadIOStrategy.java:56) at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy$WorkerThreadRunnable.run(WorkerThreadIOStrategy.java:137) at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:591) at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.run(AbstractThreadPool.java:571) at java.lang.Thread.run(Thread.java:745)