The problem is probably within the conditions of the loop.
while(result.next())
{
String AccNum = result.getString("AccountNumber");
String fNtext = result.getString("FirstName");
String mNtext = result.getString("MiddleName");
String lNtext = result.getString("LastName");
String columnNames[] = { "Account Number ", "First Name", "Last Name","Middle Name" };
String dataValues[][]=
{
{AccNum,fNtext,lNtext,mNtext}
};
table = new JTable( dataValues, columnNames );
scrollPane = new JScrollPane( table );
ListAccount.add(scrollPane);
}