JDBC SQLException

Question

public static void add(String username_, String password)
{
   try {
       conn = DBConnection.getConnection();
       String sql = "insert into userinfo (uid, user, password) values (null,'?','?')";
        pstm = conn.prepareStatement(sql);
        pstm.setString(2,username_);
        pstm.setString(3,password);
        pstm.executeUpdate();
        System.out.println("数据添加成功");
     }catch (SQLException e) {
            e.printStackTrace();
     }
   }
}

        pstm.setString(2,username_);
        pstm.setString(3,password);

``
java.sql.SQLException: Parameter index out of range (2 > number of parameters, which is 0).

为什么错?

Answer 1

?号那里的单引号去掉试试