I wrote a JDBC SQL tool to help me execute statements against databases, so I could see what was coming out via JDBC. There are character based tools (ISQL, SQL Worksheet, SQL*Plus, etc.) that let you execute statements too but they don't use JDBC, and the output is formatted with fixed-width fonts so it's a pain to read. Mine is better because you can (a) pick a driver class at runtime, (b) pick a JDBC URL at runtime (which is useful if you haven't figured out what it should look like yet), and (c) the output is formatted in an HTML table for readability. There are other advantages, such as the query timer (how many seconds did it take?) and the fact that you can just hit "back" a few times to get your old queries back too. It's a Java Servlet, since Servlets rock and that was what I was using when I needed to see what was up with some Oracle queries I was optimizing.
BTW I based the JDBC SQL Tool on an NT-Perl SQL Tool which uses Dave Roth'sWin32::ODBC module. There isn't a Unix Perl SQL Tool with DBI because by the time I wrote the NT Perl one I was already fed up with the poor performace of Perl CGI scripts, and FastCGI wasn't cutting it either due to stability issues. So I was not inclined to develop more Unix Perl CGI's that used databases.