how to populate second dropdownlist on selecting items from first one using jsp .data should be retrived from database.I prefer javascrpit.can anyone help me

hello everyone ' im beginner in java i want to know populating dropdownlist from db. for eg ; i hv 2 dropdowns project and mission.On loading jsp project should be populated from database.On selecting project type from dropdwon1 corresponding mission type should be loaded on dropdown2 ie,mission i hv a table proj-mission for that.

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December 7, 2012 at 12:26 PM

Here is an example of dependent dropdown list.

1)country.jsp:

<%@page import="java.sql.*"%>
 <html>
      <head>  
      <script language="javascript" type="text/javascript">  
      var xmlHttp  
      var xmlHttp
      function showState(str){
      xmlHttp=GetXmlHttpObject();
      if(xmlHttp==null){
       alert ("Browser does not support HTTP Request")
       return
      }
      var url="state.jsp";
      url +="?count=" +str;
      xmlHttp.onreadystatechange = stateChange;
      xmlHttp.open("GET", url, true);
      xmlHttp.send(null);
      }
      function stateChange(){   
      if (xmlHttp.readyState==4 || xmlHttp.readyState=="complete"){   
      document.getElementById("state").innerHTML=xmlHttp.responseText   
      }   
      }
     function GetXmlHttpObject(){
         var xmlHttp=null;
         try{
          xmlHttp=new XMLHttpRequest();
         }
         catch(e)
 {
 //Internet Explorer
 try
  {
  xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
  }
 catch (e)
  {
  xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
  }
 }
return xmlHttp;
}
      </script>  
      </head>  
      <body>  
      <select name='country' onchange="showState(this.value)">  
      <option value="none">Select</option>  
    <%
 Class.forName("com.mysql.jdbc.Driver").newInstance();  
 Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/test","root","root");  
 Statement stmt = con.createStatement();  
 ResultSet rs = stmt.executeQuery("Select * from country");
 while(rs.next()){
     %>
      <option value="<%=rs.getString(1)%>"><%=rs.getString(2)%></option>  
      <%
 }
     %>
      </select>  
      <br>  
      <div id='state'>  
      <select name='state' >  
      <option value='-1'></option>  
      </select>  
      </div>  
      </body> 
      </html>

December 7, 2012 at 12:27 PM

continue..

2)state.jsp:

 <%@page import="java.sql.*"%>
 <%
String country=request.getParameter("count");  
 String buffer="<select name='state' ><option value='-1'>Select</option>";  
 try{
 Class.forName("com.mysql.jdbc.Driver").newInstance();  
 Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/test","root","root");  
 Statement stmt = con.createStatement();  
 ResultSet rs = stmt.executeQuery("Select * from state where countryid='"+country+"' ");  
   while(rs.next()){
   buffer=buffer+"<option value='"+rs.getString(1)+"'>"+rs.getString(3)+"</option>";  
   }  
 buffer=buffer+"</select>";  
 response.getWriter().println(buffer); 
 }
 catch(Exception e){
     System.out.println(e);
 }
 %>

For the above code, we have created two database tables:

CREATE TABLE `country` (                                 
           `countryid` bigint(255) NOT NULL auto_increment,       
           `countryname` varchar(255) default NULL,               
           PRIMARY KEY  (`countryid`)); 



CREATE TABLE `state` (                                   
          `stateid` bigint(255) NOT NULL auto_increment,         
          `countryid` int(255) default NULL,                     
          `state` varchar(255) default NULL,                     
          PRIMARY KEY  (`stateid`));