在数据库中一起插入字符串类型变量和字节码类型变量

Question

String username = jTextField1.getText();
    String email = jTextField2.getText();
    char[] s1 = jPasswordField1.getPassword();
    char[] s2 = jPasswordField2.getPassword();
    String password = new String(s1);
    String confirmpassword = new String(s2);
    String address=jTextField6.getText();
    String phone = jTextField3.getText();
    String q1= jComboBox1.getSelectedItem().toString();
    String a1=jTextField4.getText();
    String q2= jComboBox2.getSelectedItem().toString();
    String a2=jTextField5.getText();
    String a3=a1+a2;
    MainClass m1=new MainClass();


       byte[]  sig1 = m1.sign1(a3);

        BigInteger sig2 = m1.sign2(a3);

     if (password.equals(confirmpassword))
     {
    String sql="Insert into emp values('"+(username)+"','"+(email)+"','"+(password)+"','"+(address)+"','"+(phone)+"','"+(q1)+"','"+(a1)+"','"+(q2)+"','"+(a2)+"')";
 stmt.executeUpdate(sql);

在以下代码中：

String sql="Insert into emp values('"+(username)+"','"+(email)+"','"+(password)+"','"+(address)+"','"+(phone)+"','"+(q1)+"','"+(a1)+"','"+(q2)+"','"+(a2)+"')";

我想插入sig1而不是a1和sig2而不是a2