数据库插入错误

向数据库插入一条数据，
//输入学生
public void add_student(String id,String name,String gender,
String age,String grade,String class_bj,String performance){
// System.out.println(mf.getId_field().getText());
try{
// stem = con.createStatement();
String s = “insert into tb_stu values(?,?,?,?,?,?,?)”;
statement = con.prepareStatement(s);
statement.setString(1, id);
statement.setString(2, name);
statement.setString(3, gender);
statement.setString(4, age);
statement.setString(5, grade);
statement.setString(6, class_bj);
statement.setString(7, performance);
statement.executeUpdate();
// String s = “insert into tb_stu values(”+id+","+name+","+gender+","+age+","
// +grade+","+class_bj+","+performance+")";
// stem.execute(s);

}catch(SQLException e){
e.printStackTrace();
}

}
为啥用注释的方法插入会出现下列错误，未注释的预处理方法可以成功。
[错误信息]