-----Mensaje original-----
De: Hans Bergsten [mailto:[EMAIL PROTECTED]
Enviado el: Viernes, 16 de Abril de 2004 11:07 a.m.
Para: Tag Libraries Users List
Asunto: Re: More SQL Date problems
Justyna Horwat wrote:
> Hans,
>
> I looked into the SQL problem and consulted with the JDBC specification
> lead, Jonathan Bruce. Jonathan said that what JSTL is doing is correct:
> when setObject(index, null) is passed in a null value this should be
> converted by the driver to an SQL null.
>
> This behavior is in fact enforced as part of the J2EE compatibility in
> the CTS. The JDBC Driver Test Suite is publicly accessible and can be
> used to weed out the JDBC drivers that are not compatible.
Thanks Justyna! So, it sounds like the case is closed. A JDBC driver
that doesn't handle setObject(index, null) the way JSTL expects isn't
spec compliant.
Hans
> Hans Bergsten wrote:
>
>> Wolfgang Röckelein wrote:
>>
>>> Hi,
>>>
>>> at JDBC level there are two different possibilities to set a
>>> parameter value to null: with setNull and setting to null. Depending
>>> on the driver sometimes only on of these methods work, and when it
>>> does not work, you see the "java.sql.SQLException: Invalid column
>>> type" error you see.
>>>
>>> I think this was already changed or discussed sometime during the
>>> standard taglib development.
>>
>>
>>
>> Right. I was looking at the code for JSTL in the CVS archive, and it
>> calls setObject(index, null) when passed a null value, and there's a
>> comment that this should be converted by the driver to an SQL null.
>> Browsing through the JDBC JavaDocs and the JDBC spec, there seems to
>> be some support for this claim, but it's not 100% clear. It's possible
>> that the driver Keith is using doesn't handle it, and maybe it would
>> be better if JSTL used setNull(). The reason it doesn't is that it
>> would required additional type info for the <sql:param> case.
>>
>> Pierre, this may be something to look at again for JSTL.next.
>>
>> Keith, a work-around for this would be:
>>
>> <fmt:parseDate value="${param.dob}" var="parsed_dob"
>> pattern="dd-MM-yyyy" />
>>
>> <c:choose>
>> <c:when test="${!empty parsed_dob}">
>> <sql:update>
>> INSERT INTO resource_registry (resource_id, dob)
>> VALUES (res_id_seq.NEXTVAL, ? )
>> <sql:dateParam value="${parsed_dob}" type="date"/>
>> </sql:update>
>> </c:when>
>> <c:otherwise>
>> INSERT INTO resource_registry (resource_id)
>> VALUES (res_id_seq.NEXTVAL)
>> </sql:update>
>> </c:otherwise>
>> </c:choose>
>>
>> If the real case involves many parameters that may be null, this
>> gets ugly, but if it's just this one, it may be okay.
>>
>> Hans
--
Hans Bergsten <[EMAIL PROTECTED]>
Gefion Software <http://www.gefionsoftware.com/>
Author of O'Reilly's "JavaServer Pages", covering JSP 2.0 and JSTL 1.1
Author of O'Reilly's "JavaServer Faces", covering JSF 1.0
Details at <http://TheJSPBook.com/>
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