im Получение ошибки в строке набора результатов

Question

<%@ page import= "java.sql.*" 
     import= "java.util.*"%> 

<% 
     Class.forName("com.mysql.jdbc.Driver").newInstance(); 
     Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/user","root",""); 
     Statement st = con.createStatement(); 

     String name = request.getParameter("name"); 
     String username = request.getParameter("user"); 
     String pass = request.getParameter("pas"); 
     String cpass = request.getParameter("cpas"); 


     String sql2 = "select * from user where user='"+username+"';"; 
     ResultSet rs = st.executeQuery(sql2); 
     if(rs.next()) 
     { 
      response.sendRedirect("index.html?err=Username already taken"); 
     } 
     else 
     { 

     String sql = "insert into user values('"+name+"', '"+username+"','"+pass+"',"+cpass+");"; 
     st.executeUpdate(sql); 

     response.sendRedirect("blank.html"); 
     } 

%> 

Answer 1

Class.forName ("com.mysql.jdbc.Driver"). NewInstance(); Connection con = DriverManager.getConnection ("jdbc: mysql: // localhost: 3306/user", "root", ""); Заявление st = con.createStatement();

String name = request.getParameter("name"); 
    String username = request.getParameter("user"); 
    String pass = request.getParameter("pas"); 
    String cpass = request.getParameter("cpas"); 


    String sql2 = "select * from user where user='"+username+"';"; 
    ResultSet rs = st.executeQuery(sql2); 
    if(rs != null && rs.next()) 
    { 
     response.sendRedirect("index.html?err=Username already taken"); 
    } 
    else 
    { 

    String sql = "insert into user values('"+name+"', '"+username+"','"+pass+"',"+cpass+");"; 
    st.executeUpdate(sql); 

    response.sendRedirect("blank.html"); 
    }