Programming error

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

<%

Connection con=null;
ResultSet rs=null;
Statement stmt=null;
int No=0;

try{
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
con=DriverManager.getConnection("jdbc:odbc:Advdsn");
stmt=con.createStatement();
rs=stmt.executeQuery("select OrderNo from OrderTab ");
while(rs.next())
{
int Ono=rs.getInt(1);
No=Ono+1;
}

}
catch(SQLException se)
{out.println("Database error="+se.getMessage());
}

catch(Exception e)
{out.println("Error="+e.getMessage());
}
//System.out.println(No);

%>

<HTML>
<HEAD>
<TITLE> Place Order </TITLE>
<script type="text/javascript">
function checkName(text)
{
if(isNaN(text)){ return 1;}
else{alert("Invalid Name! The only charachters accepted are A - Z and a - z");return 0;}
}
function checkPhoneNumber(num) {
if(isNaN(num)){alert("Invalid Phone Number! The only characters permitted are 0 to 9"); return 0;}
else{return 1;}
}

function Validate()
{
var name=document.form.Name;
var phone=document.form.PhoneNo;
var email=document.form.Email;
if(document.form.OrderNo.value=="")
{ alert("Please enter valid OrderNo");
return false;
}
if(name.value=="")
{ alert("Please enter valid Client's Name");
return false;

}
if (checkName(name.value)==false){
name.value="";
name.focus();
return false;
}
if(document.form.Address.value=="")
{ alert("Please enter valid Client's Address");
return false;
}
if(email.value=="")
{ alert("Please enter valid Email Id");
return false;
}
apos=email.value.indexOf("@")
dotpos=email.value.lastIndexOf(".")
if (apos<1 || dotpos-apos<2)
{
alert("Invalid Email Id")
email.value=="";
email.focus();
return false;
}

if(phone.value=="")
{ alert("Please enter valid PhoneNo");
return false;
}
if (checkPhoneNumber(phone.value)==false){
phone.value="";
phone.focus();
return false;
}
return true;
}
</script>

</HEAD>

<BODY BGCOLOR="lightblue">
<marquee behavior="alternate" scrollamount=5 scrolldelay=10>
<h1><font size=4 face="Stroustroup" color="#993355">Advertisement Management System</h1></font></marquee><br>

<hr color="green">
<form method="post" onsubmit="return Validate();" name="form" action="http://localhost:8080/ProjectAd/Orders">
<center>
<table>
<tr><td>Order No:</td><td><input type="text" name="OrderNo" size=25 value="<%=No%>" readonly></td></tr>
<tr><td>Name:</td><td><input type=text name="Name" size=25 ></td></tr>
<tr><td>Address:</td><td><textarea name="Address" rows=5 cols=25 size=25></textarea></td></tr>
<tr><td>Email:</td><td><input type=text name="Email" size=25></td></tr>
<tr><td>PhoneNo:</td><td><input type=text name="PhoneNo" size=25></td></tr>

<tr><td><a href="http://localhost:8080/ProjectAd/Orders"><input type=submit name=submit value="InsertOrder"></a></td></tr>

<tr><td><input type=reset name=reset value="Reset"></td></tr>
</table>
</center>
<a href="http://localhost:8080/ProjectAd/Update.jsp"><b><h4 align=center>Update Orders</h4></b></a>
<a href="http://localhost:8080/ProjectAd/Delete.jsp"><b><h4 align=center>Delete Orders</h4></b></a>
<a href="http://localhost:8080/ProjectAd/View.jsp"><b><h4 align=center>View Orders</h4></b></a>
<a href="http://localhost:8080/ProjectAd/PlaceOrd.jsp"><b><h4 align=center>Back </h4></b></a></p>
<p align=center><a href="http://localhost:8080/ProjectAd/MainPage.html"><img src="images/home_ap.jpg" height=20 width=20></a>

</form>
<hr color="green">
</BODY>
</HTML>

in this i want that order no should no get change that is if there 5 orders in database and if some user deletes its own then order no gets converted to 4 but it should not happen if out of 5 orderno 3 is deleted then other order no. should remain same i.e 1,2,4,5 and order no. 3 that is blank now should get replaced by order no 4 ieblank spaces should get replaced by their next order no. but order no. should not get change then how to do this please reply me thank you sir.

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