XSQL with optional parameters

Question

I am trying to create an XSQL page that has optional parameters.
What I mean is, I would like the page to return all records for a query when the following url is used http://myserver.com/my_inventory.xsql
And I would like the page to return limited records for a query when the following url is used http://myserver.com/my_inventory.xsql?item=123
I have been trying the following with no success. Any suggestions?
<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="rowset2inventorylevel.xsl"?>
<xsql:if-param name="item" exists="no">
<xsql:query connection="myconn" tag-case="lower" xmlns:xsql="urn:oracle-xsql">
select m.item_no
, m.description
, m.qty_on_hand
, nvl(p.gross_wt,0) weight
from item_master m
, item_price p
where m.item_no = p.item_no
and m.status_flag='A'
and m.discontinue_flag = 'N'
order by m.item_no
</xsql:query>
</xsql:if-param>
<xsql:if-param name="item" exists="yes">
<xsql:query connection="myconn" tag-case="lower" xmlns:xsql="urn:oracle-xsql">
select m.item_no
, m.description
, m.qty_on_hand
, nvl(p.gross_wt,0) weight
from item_master m
, item_price p
where m.item_no = p.item_no
and m.status_flag='A'
and m.discontinue_flag = 'N'
and m.item_no = ?
order by m.item_no
</xsql:query>
</xsql:if-param>

Answer 1

The easy, but less optimal way, is to use OR in your where clause:
rewrite "and m.item_no = ?" to "and m.item_no = ? or ? is null" - and remember to include the parameter twice in bind-params.
The "right" way to do this, meaning a more optimal access path, is to use stored procedures that returns REF CURSORs. Then in the stored procedure you look for NULL and change the where clause accordingly.