sql and&or用法 实现jsp邮箱或者用户名登录

     try {            //链接字符串             String driver ="com.mysql.jdbc.Driver";            //加载驱动             Class.forName(driver);             //建立数据库连接             Connection   con = (Connection) DriverManager.getConnection(url,user, dbpassword);            if(con==null){                System.out.println("can't open JDBConnection");            }            //sql语句            String sql = "select * from user.user where (username=? or email=? )and password=?";            PreparedStatement pstmt=(PreparedStatement) con.prepareStatement(sql);             pstmt.setString(1,this.Name); //第1个？字符的替换            pstmt.setString(2,this.Name); //第2个？字符的替换            pstmt.setString(3,this.Password);//第3个？字符的替换            //pstmt.setString(4,this.Password);//第4个？字符的替换            System.out.println(sql);            System.out.println(getName());            System.out.println(getPassword());            ResultSet rs=pstmt.executeQuery();//执行语句后，产生单个结果集的语句            if(rs.next())            {                System.out.println(rs.getString("username"));                System.out.println("PASS");                result=true;            }            else            {                System.out.println("FALL");                result=false;            }            pstmt.close();//3个关闭PreparedStatement，ResultSet，Connection            rs.close();            con.close();        } catch (Exception e) {            // TODO Auto-generated catch block            e.printStackTrace();        }        return result;

总结：测试的时候看看是不是测试的用户名写错了= =