如何在mysql中

Question

String user = request.getParameter("uname"); 
String pwd = request.getParameter("pass"); 
String pwd1 = request.getParameter("pass"); 
String pwd2 = request.getParameter("pass"); 

try{ 
    Class.forName("com.mysql.jdbc.Driver"); 
    String url = "jdbc:mysql://localhost:3306/logindb"; 
    Connection con = DriverManager.getConnection(url, "root", "root"); 

    String sql = "select * from register"; 
    PreparedStatement ps = con.prepareStatement(sql); 
    ps.setString(1, pwd); 
    ps.setString(2, request.getParameter("uname")); 
    ResultSet rs = ps.executeQuery(); 
    if(rs.next()) 
    { 
     sql = "update register set pass=? where uname=? "; 
     ps = con.prepareStatement(sql); 
     ps.setString(1, pwd); 
     ps.setString(2, request.getParameter("uname")); 
     ps.executeUpdate(); 
     out.println("password changed"); 

    } 
} 
catch(Exception e) 
{ 
    out.println(e); 
} 

更改密碼列這是我的代碼，它會告訴我這樣一個錯誤

值java.sql.SQLException：參數指標超出範圍（1>參數的數量，這是0）**

Answer 1

這裏：

String sql = "select * from register"; 
PreparedStatement ps = con.prepareStatement(sql); 
ps.setString(1, pwd); 
ps.setString(2, request.getParameter("uname")); 

您嘗試設置是不存在的參數。看起來像複製粘貼錯誤。最後2行不應該在那裏。