Thank you for the quick response, jr158900.
I am sorry, but I forgot to mention in the first post that the web application itself is currently working on Tomcat, so I don't think the problem resides in the source code. I am planning a transition of the server from Tomcat to Glassfish, but am unable because of the JSTL issue in discussion.
Glassfish currently does not make use of the resource definitions in WEB-INF/context.xml file that Tomcat uses, so instead I created a connection pool and a JDBC resource in the admin GUI to be used from my web application. The mystery is that the ping to the connection pool works, but the JSTL sql tag does not.
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