How to retrive values from the database

[rushikesh kale]

Hi Guys!
I Have a little problem in retriving the value of Data item from my database . I am also using Beans for my JSP page. In my Bean file i write follg. code to retrive value of Price :

public int getPrice()
{
 try 
 {     ResultSet priceis =s.executeQuery("Select * from supply where ID = "+getId());
       while(priceis.next())
       {
         price=Integer.parseInt(priceis.getString(3));
}
 }
 catch(Exception e)
 {
   e.printStackTrace();
 }
  return price;
}
//END 

In jsp i use:- Price :<jsp:getProperty name ="product" property="price"/><BR>
But i failed ! please help me!
thanks

[edited to add code tags]
[ January 29, 2005: Message edited by: Jeanne Boyarsky ]

[Craig Jackson]

Can you elaborate more on what

But i failed

means?

Are you generating an error on the jsp page and/or are you not getting the desired results?

A little more information would be helpful.

Thanks.

[rushikesh kale]

Hi Craig
I failed to retrive the value of price from database.

[Craig Jackson]

Well, the first thing I would do is verify that data exists based on your query for specific "ID" and you are able to return the desired results.

I would do this by using a plain old regular test Java program(NO JSP) with your java bean. This should be done before we insert this same java bean code into your JSP page.

 ResultSet priceis =s.executeQuery("Select * from supply where ID = "+getId()); 

[rushikesh kale]

Well i tried hard but still i get the error as Null pointer exception , thats why now i try to send you my program.
1.name coonectionBean.java)
Code:
package supply;
import java.io.*;
import java.sql.*;

public abstract class connectionBean
{
private String driver="sun.jdbc.odbc.JdbcOdbcDriver";
private String url="jdbc dbc:rushi";
protected Connection conn;
public connectionBean() {}
public void connect() throws Exception
{
Class.forName(driver);
conn=DriverManager.getConnection(url);
System.out.println("I connect");
}
public abstract void cleanup() throws Exception;
public void takedown() throws Exception
{
cleanup();
conn.close();
}

}

[rushikesh kale]

Sorry I by mistake fwd a previous incomplete reply:


Well i tried hard but still i get the error as Null pointer exception , thats why now i try to send you my program.
1.name coonectionBean.java)
Code:
package supply;
import java.io.*;
import java.sql.*;

public abstract class connectionBean
{
private String driver="sun.jdbc.odbc.JdbcOdbcDriver";
private String url="jdbc dbc:rushi";
protected Connection conn;
public connectionBean() {}
public void connect() throws Exception
{
Class.forName(driver);
conn=DriverManager.getConnection(url);
System.out.println("I connect");
}
public abstract void cleanup() throws Exception;
public void takedown() throws Exception
{
cleanup();
conn.close();
}
}

2.name: Order.java
Code:

package supply;
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.sql.*;
public class Order extends connectionBean  
{
private int id,disc,price,qty,total;
private String name;
Statement s;
ResultSet priceis;
    public Order()
{  
super();
id=1;
   disc=0;
price=100;
qty=1;
total=100;
name="xyz";
    }
public void setId(int i){id=i;}
public void setQty(int q){qty=q;}
public void setDisc(int d){disc=d;}
public int getId(){return id;}
public int getQty(){return qty;}
public int getDisc(){return disc;}
public int getPrice(int i) 
{
try
 {
s=conn.createStatement();
    priceis =s.executeQuery("Select * from supply where ID ="+i);
while(priceis.next())
{
String sprice=priceis.getString(3);
price=Integer.parseInt(sprice);

}
 }
catch(Exception e)
 {
   e.printStackTrace();
        }
 return price;
}
public String getName() throws Exception
{
ResultSet namepresent =s.executeQuery("Select NAME from supply where ID="+getId());
        if(namepresent.next())
         {
  String name=namepresent.getString(2);
         }
 return name;
  }
public int getTotal(int i) throws Exception
{
   total=(getPrice(i)-getDisc())*getQty();
   return total;
}
public void cleanup() throws Exception
{
s.close();
}

}
 
3>name  :-o	  rderMain.jsp
  Code:
<jsp:useBean id="product" class="supply.Order"/>
<%@page import="java.awt.*"%>
<%@page import="java.awt.event.*"%>
<%@page import="java.io.*"%>
<%@page import="java.sql.*"%>
<%! int id,qty,disc; 
       String s1,s2,s3;%>
<% s1=request.getParameter("id");%>
<% s2= request.getParameter("qty");%>
<% s3= request.getParameter("disc");%>
<%try {
%>
<%  id=Integer.parseInt(s1);%>
<% qty=Integer.parseInt(s2);%>
<% disc=Integer.parseInt(s3);%>
   <% }
catch(Exception e)
 {
   e.printStackTrace();
 }

%>
<jsp:setProperty name ="product" property ="id" value='<%=id%>'/>
<jsp:setProperty name="product" property="qty" value='<%=qty%>'/>
<jsp:setProperty name ="product" property ="disc" value='<%=disc%>' />
ID :<jsp:getProperty name ="product" property="id"/><BR>
Quantity:<jsp:getProperty name ="product" property="qty"/><BR>
Discount :<jsp:getProperty name ="product" property="disc"/><BR>
Price :<jsp:getProperty name ="product" property="price" param='<%=id%>' /><BR>
Name :<jsp:getProperty name ="product" property="name" /><BR>
Total :<jsp:getProperty name ="product" property="total"/><BR>

4>I take value of id,qty,disc using OrderMain.html page.
5>I am using Java Web server

[edited to add code tags]
[ January 30, 2005: Message edited by: Jeanne Boyarsky ]

[Craig Jackson]

Can you provide a copy of the exact error stack? I am trying to see if this is a JDBC error or a JSP error.


Thanks.

[rushikesh kale]

hi
Now i changed my code littile bit,In fuction getPrice in Order.java bean instead of taking parameter i use getid fuction as follows:
public int getPrice()
{try
{
s=conn.createStatement();
priceis =s.executeQuery("Select * from supply where ID ="+this.getId());
while(priceis.next())
{
String sprice=priceis.getString(3);
price=Integer.parseInt(sprice);
}
}
catch(Exception e)
{
e.printStackTrace();
}
return price;
}
Now I atleast dosent get the error on web page.but i am still not getting the price from the table .i am getting default value of price i.e. price=100.

This is the error which i got on my java web server:
javawebserver: at com.sun.server.http.pagecompile.jsp.runtime.JspServlet.runSer
vlet(JspServlet.java:469)
javawebserver: at com.sun.server.http.pagecompile.jsp.runtime.JspServlet.proces
sJspPage(JspServlet.java:259)
javawebserver: at com.sun.server.http.pagecompile.jsp.runtime.JspServlet.servic
e(JspServlet.java:97)
javawebserver: at javax.servlet.http.HttpServlet.service(HttpServlet.java:840)
javawebserver: at com.sun.server.ServletState.callService(ServletState.java:226
)
javawebserver: at com.sun.server.ServletManager.callServletService(ServletManager.java:936)
javawebserver: at com.sun.server.ProcessingState.invokeTargetServlet(ProcessingState.java:423)
javawebserver: at com.sun.server.http.HttpProcessingState.execute(HttpProcessingState.java:79)
javawebserver: at com.sun.server.http.stages.Runner.process(Runner.java:79)
javawebserver: at com.sun.server.ProcessingSupport.process(ProcessingSupport.java:294)
javawebserver: at com.sun.server.Service.process(Service.java:204)
javawebserver: at com.sun.server.http.HttpServiceHandler.handleRequest(HttpServiceHandler.java:374)
javawebserver: at com.sun.server.http.HttpServiceHandler.handleRequest(HttpServiceHandler.java:166)
javawebserver: at com.sun.server.HandlerThread.run(HandlerThread.java:162)

Thanks