how to load value in dropdown list after selecting value from first dropdown list using javascript

View Answers

March 16, 2012 at 10:54 AM

1)country.jsp:

<%@page import="java.sql.*"%>
 <html>
      <head>  
      <script language="javascript" type="text/javascript">  
      var xmlHttp  
      var xmlHttp
      function showState(str){
      if (typeof XMLHttpRequest != "undefined"){
      xmlHttp= new XMLHttpRequest();
      }
      else if (window.ActiveXObject){
      xmlHttp= new ActiveXObject("Microsoft.XMLHTTP");
      }
      if (xmlHttp==null){
      alert("Browser does not support XMLHTTP 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   
      }   
      }
      </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>

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`));