jstl sql taglib database error codes

[Marie Griffiths Remove Rubbish]

I am using a <c:sql:update theat sometimes hives a duplicate row error freom
the database.
How do I handle this from just jstl?
I am using the sun sql taglib connecting to a MS SQL Server database.
I can handle this by skipping into jsp but I would prefer to keep it in pure
jstl. I also cannot get the SQLexception error
e.g.

...............
<%
try

%>
<sql:update ................
%>
catch( SQLexception e)
{
}
<%
....................