Java+SQL executeQuery and return results

Question

I'm new to java and I have this problem when I'm trying to fetch data from SQL DB and show it when he logs in.

sql = "select nom from adherent where id_adherent=3";
try {
    pst = con.prepareStatement(sql);
    ResultSet rs = pst.executeQuery();
} catch (SQLException e) {
    JOptionPane.showMessageDialog(null, "here 1");
}

try {
    if (rs.next()) {
        String sum = rs.getString("select *");
        nom.setText(" " + sum);
    }
} catch (SQLException e) {
    JOptionPane.showMessageDialog(null, "here 2");
}

Thank You.

Answer 1

Your don't need two try and catch, because you define your ResultSet in the first try block, so you can't use this, in another try, so make this instead :

sql = "select nom from adherent where id_adherent=3";
try {
    pst = con.prepareStatement(sql);
    ResultSet rs = pst.executeQuery();
    if (rs.next()) {
        String sum = rs.getString("nom");
        nom.setText(" " + sum);
    }
} catch (SQLException e) {
    JOptionPane.showMessageDialog(null, "here 1");
}

---

If you want something perfect and far of any syntax error, or SQL Injection, you have to use the operator ? of PreparedStatement for example :

sql = "select nom from adherent where id_adherent = ?";
//--------------------------------------------------^
try {
    pst = con.prepareStatement(sql);
    pst.setInt(1, id_adherent);//you can set any number in id_adherent in your case 3
    ....

Answer 2

I think this will help you:

sql = "select nom from adherent where id_adherent=3";

try {
    pst = con.prepareStatement(sql);
    ResultSet rs = pst.executeQuery();

    if (rs.next()) {
        String sum = rs.getString("nom");
        nom.setText(" " + sum);
    }  
}
catch (SQLException e) {
    JOptionPane.showMessageDialog(null, "here 1");
}