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paging in jsp for multiple queries

arvindmpai
Greenhorn

Joined: Nov 06, 2001
Posts: 1
hi! i would like someone to help me with paging in jsp.my code uses multiple queries and the result is that when i press the next button i get a java null pointer exception.
my code is as follows:Please help,matter pretty urgent
<%@ page language ="java" import=" java.sql.* " %>
<%
String a=request.getParameter("a");
String b=request.getParameter("b");
String c=request.getParameter("c");
String d=request.getParameter("d");
String e=request.getParameter("e");
String f=request.getParameter("f");
String g=request.getParameter("g");
String h=request.getParameter("h");
String i=request.getParameter("i");

String point=request.getParameter("point");
int next,previous;
int pointer=0;
int count=0;
int maxrecords=5;

try
{

Class.forName("gjt.org.mm.mysql.Driver");

Connection myConn=DriverManager.getConnection("jdbc:mysql://servername/password/username");
Statement stmt = myConn.createStatement();
String sql="";
if(point==null)
{
next=0;
previous=0;
//previoos=previous+1;
// change next=next+1;
}
else
{
next=Integer.parseInt(point);
previous=Integer.parseInt(point);
}
sql="select * from tablename where id>="+(next+1);
if(a.length()>0 &&(a!=null))
{
sql= sql + " and a='"+a+"'";
}
if(b.length()>0 &&(b!=null)&& (!b.equals("empty")))
{
sql= sql + " and b='"+b+"'";
}
if(c.length()>0 &&(c!=null))
{
sql= sql + " and c='"+c+"'";
}
if(d.length()>0 &&(d!=null))
{
sql= sql + " and d>='"+d+"'";
}
if(e.length()>0 &&(e!=null))
{
sql= sql + " and e<='"+e+"'";
}
if(f.length()>0 &&(f!=null))
{
sql= sql + " and f>='"+f+"'";
}
if(g.length()>0 &&(g!=null))
{
sql= sql + " and g<='"+g+"'";
}
ResultSet rs=stmt.executeQuery(sql);
ResultSetMetaData rm1 = rs.getMetaData();
//out.println(sql);
%>

<TABLE WIDTH="80%" BORDER="1" ALIGN="center">
<TR>
<Th ALIGN="center" BGCOLOR="#CCFFFF"><B><%=rm1.getColumnLabel(6)%></B></Th>
<Th ALIGN="center" BGCOLOR="#CCFFFF"><B><%=rm1.getColumnLabel(7)%></B></Th>
<Th ALIGN="center" BGCOLOR="#CCFFFF"><B><%=rm1.getColumnLabel(8)%></B></Th>
</TR>
<%
if(rs.next())
{
do
{
out.println("<tr><td>"+ rs.getString(rm1.getColumnLabel(6))+ "</td><td>" + rs.getString(rm1.getColumnLabel(7)) + " </td><td>"
+ rs.getString(rm1.getColumnLabel(8)) + " </td></tr>");

//rs1.getString(rm1.getColumnlabel(1)) + " </tr></tr>");
next++;
//next--;
}while((rs.next())&(next % maxrecords !=0));
//while((rs.previous())&(next % maxrecords !=1));
}

out.println("</table>");
if(previous >1)
{
previous=previous-maxrecords;
//previous=previous+maxrecords;
out.println("<a href='http://localhost:8080/paginginjsp.jsp?point="+previous+"'> previous</a>    ");
}
if(rs.next())
{
out.println("<a href='http://localhost:8080/paginginjsp.jsp?point="+next+"'> next </a>");
}

//pw.println("</body></html>");
myConn.close();
}
catch(SQLException exp)
{
out.println("<H2>Database Error</H2> <B>" + exp.getMessage() + "</B><H4> Please Try Sometime Later</H4>");
}

%>
Sandy Goh
Greenhorn

Joined: Aug 25, 2003
Posts: 6
hi. did you manage to get it? cos currently i need that code too.. pls let me know if you are able to do it.
Bear Bibeault
Author and ninkuma
Marshal

Joined: Jan 10, 2002
Posts: 61433
    
  67

Welcome to the Ranch arvindmpai!
You'll find this forum a great place to seek help on JSP pages, and there aren't many rules you'll have to worry about, but one is that proper names are required. Please take a look at the JavaRanch Naming Policy and change your display name to match it.
I'd also like to suggest that when posting code to the forums, that you use the UBB code tags. That way, the formatting of your code will be preserved.
Also, this very subject, the paging of large datasets, has been discussed a number of times in these forums. You might find some useful hints by searching this and the Servlets forum for information on paging.
Thanks!
bear
JSP Bartender
[ August 25, 2003: Message edited by: Bear Bibeault ]

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