Question

I am making an application in NetBeans (java). This application has unique id combination of string and integer like abc/111 or xyz/253 and the integer part should increase by when a new entry takes place in the database i.e. abc/112 and xyz/254.

The problem is the value of integer part increase until it has reached 10 in a proper way but after that it does not increase and remain same for further entries in database.

I used the following code –

try{
    String sql = "SELECT RegNumber FROM Death ORDER BY RegNumber DESC   ";
    pst = conn.prepareStatement(sql);

    rs = pst.executeQuery();

    if (rs.next()) {

        String add1 = rs.getString("RegNumber");
        String[] parts= add1.split("/");
        String part1= parts[0];
        String part2= parts[1];
        int a,b;
        a= Integer.parseInt(part2);
        b=a+1;

        jTextField20.setText(""+part1+"/"+b);


        JOptionPane.showMessageDialog(null, "done");
    }
   }

“Integer part increase till 10” means that if I start the first value of id in database like abc/1 then new id generates automatically for the next entry with the increasing value 1 that is abc/2 and for next entry it is abc/3 and so on in sequential order like this: abc/4, …, abc/10

But when it has reached abc/10 the new generated id remains same i.e. abc/10 for every new entry in database. (I am using MS Access 2007 and the id is of text type). The first id in the database is created by the application itself.

If anyone has another alternative to generate id, please tell me.

Answer 1

The problem is that

String sql = "SELECT RegNumber FROM Death ORDER BY RegNumber DESC   ";

will sort on descending alphabetic order, and alphabetically speaking

"abc/9" > "abc/10"

and that’s why your program always fetches 9 over and over again…

I think you will have to split up that column for storage, and store the numeric part as an actual number type in the database. That’s probably not as hard as it sounds, you can always sort on 2 fields

String sql = "SELECT RegNumber FROM Death ORDER BY RegString DESC, RegNumber DESC   ";

You could also consider using a SERIAL (autoincrement) datatype for the RegNumber part in certain cases (ie if RegNumber is not reset eg when the string part changes) to simplify your insertion logic further.