How to retrieve data by using combo box value in jsp?

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How to retrieve data by using combo box value in jsp?

Hi Friends,

When i click combobox value in jsp form page, it will diplay related value.... I am using only this page.. not get value from another page...
For Example, in Student.jsp... when i click student id in combo box, the related student name will be display. I can stored all student id stored in combo box from database.. by using select*from studentinformation;

But when i click combobox the related student name did not display...

On friend gave the follwing link

http://www.roseindia.net/jsp/comboSelect.shtml ull pointer exception

if i am trying null pointer exception will be occured.. I need immediately respose from u......




View Answers

February 24, 2010 at 3:34 PM

Hi i try the URL given above
http://www.roseindia.net/jsp/comboSelect.shtml
and i run that project with my settings
it works


I'm using enterprisedb ,and glassfish v2 and netbeans
change these settings to your settings and run app.

My sample table script is below.
CREATE TABLE "user"
(
"name" character varying(100),
eid character varying
)

--------code ------------------------------getuser.jsp----------------------------------
<%@ page import="java.sql.*" %>
<%
String emp_id = request.getParameter("emp_id").toString();
String data ="";

Connection conn = null;
String url = "jdbc:edb://127.0.0.1:5444/";;
String dbName = "nb";
String driver = "com.edb.Driver";
String userName = "enterprisedb";
String password = "OLIMPUS";

int sumcount=0;
Statement st;
try {
Class.forName(driver).newInstance();

conn = DriverManager.getConnection(url+dbName,userName,password);
String query = "select name,eid from public.user where name='"+emp_id+"'" ;

st = conn.createStatement();
ResultSet rs = st.executeQuery(query);
while(rs.next())
{
data = ":" + rs.getString(1)+" " + rs.getString(2) ;
}


out.println(data);
}
catch (Exception e) {
e.printStackTrace();
}
%>

---------------------------combobox.jsp------------------------------------
------------
<%@ page import="java.sql.*" %>
<html>
<head>
<style>
A:hover {text-decoration: none;

border: 0px;
font-size:14pt;
color: #2d2b2b; }
</style>

<link rel="stylesheet" type="text/css" href="datepicker.css"/>


<script type="text/javascript">
function showEmp(emp_value)
{
if(document.getElementById("emp_id").value!="-1")
{
xmlHttp=GetXmlHttpObject()
if (xmlHttp==null)
{
alert ("Browser does not support HTTP Request")
return
}
var url="getuser.jsp"
url=url+"?emp_id="+emp_value

xmlHttp.onreadystatechange=stateChanged
xmlHttp.open("GET",url,true)
xmlHttp.send(null)

}
else
{
alert("Please Select Employee Id");
}
}

function stateChanged()
{
document.getElementById("ename").value ="";
document.getElementById("emp_id").value ="";
if (xmlHttp.readyState==4 || xmlHttp.readyState=="complete")
{

var showdata = xmlHttp.responseText;
var strar = showdata.split(":");

if(strar.length==1)
{
document.getElementById("emp_id").focus();
alert("Please Select Employee Id");
document.getElementById("ename").value =" ";
document.getElementById("emp_id").value =" ";

}
else if(strar.length>1)
{
var strname = strar[1];
document.getElementById("emp_id").value= strar[2];
document.getElementById("ename").value= strar[1];
}

}
}

function GetXmlHttpObject()
{
var xmlHttp=null;
try
{
// Firefox, Opera 8.0+, Safari
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>
<form name="employee">
<br><br>
<table border="0" width="400px" align="center" bgcolor="#CDFFFF">
<div id="mydiv"></div>
<tr><td><b>Select Employee Id</b></td><td>
<select name="semp_id" onchange="showEmp(this.value);">
<option value="-1">Select</option>
<%



Connection conn = null;
String url = "jdbc:edb://127.0.0.1:5444/";;
String dbName = "nb";
String driver = "com.edb.Driver";
String userName = "enterprisedb";
String password = "OLIMPUS";

int sumcount=0;
Statement st;
try {
Class.forName(driver).newInstance();

conn = DriverManager.getConnection(url+dbName,userName,password);
String query = "select name from public.user";

st = conn.createStatement();
ResultSet rs = st.executeQuery(query);
%>

<%
while(rs.next())
{
%>

<option value="<%=rs.getString(1)%>"><%=rs.getString(1)%></option>

<%
}
%>

<%

}
catch (Exception e) {
e.printStackTrace();
}

%>

</select>
</td></tr>


<tr><td ><b>Employee Id:</b></td><td><input type="text" name="emp_id" id="emp_id" value=""></td></tr>
<tr><td><b>Employee Name:</b></td><td><input type="text" name="emp_name" id="ename" value=""></td></tr>

</table>
</form>

<table border="0" width="100%" align="center">


<br>
<br>


</table>
</body>
</html>

Hope this helpful.
Best Regards.

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