CODEWITHSUNDEEP
javamysqlnetbeansincrement
Kokotech
Kokotech

Reputation: 21

How to increment the ID automatically in java NetBeans using mysql and to insert the current year or date inside the ID

hello evryone am working a student management system and for saving students information in mysql database am using an auto-increment but i want make all StudentID to start with "ST" followed by the "Currentyear" then a number that will be incremented automaticly and be didplayed in a jTextField i have designed and named "jTextFieldstudentid" the probeme is when i run the file, the output is not corresponding to what i need, in the students Table on mysql dB the last ID = "ST2020001" but in the jTextField am getting "ST20200012020002" instead of "ST2020002" please help, i dont know if there is something wrong with my code.

private void StudentAutoID()
     {
         try {
            String sql="SELECT StudentID FROM students ORDER BY StudentID DESC LIMIT 1";       
            PreparedStatement  pst=con.prepareStatement(sql);
            ResultSet rs=pst.executeQuery();
            if(rs.next())
                {
                Date d=new Date();
                int year=d.getYear();
                int currentYear = year+1900;
                String rnno=rs.getString("StudentID");
                int co=rnno.length();
                String txt= rnno.substring(0, 2);
                String num=rnno.substring(2, co);
                int n=Integer.parseInt(num);
                n++;
                String snum=Integer.toString(n);
                String ftxt=txt+currentYear+snum;
                jTextFieldstudentid.setText(ftxt);

                }
            else
                {
                jTextFieldstudentid.setText("ST2020000");
                }
            } catch (Exception e) {
                JOptionPane.showMessageDialog(rootPane, e);
            }

     }```

Upvotes: 1

Views: 598

Answers (1)

Patrycja Wegrzynowicz
Patrycja Wegrzynowicz

Reputation: 737

The problem is in this line:

String num=rnno.substring(2, co);

Your substring includes the year as well.

If you change it to:

String num=rnno.substring(6, co);

it will work as expected.

However, I would reconsider the model. It might be better to keep atomic fields for a year and a numerical id; and based on those fields to calculate the student id in the java code without the invocations of the substring method.

Upvotes: 2

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