One way is to use any of the SQL::Statement DBDS - AnyData, CSV, DBM, etc. with the new IMPORT() function which allows heterogeneous joins across DBMS types. For example: 
my $csv_dbh = DBI->connect( 'dbi:CSV...);
my $ora_dbh = DBI->connect( 'dbi:Oracle...);
my $fir_dbh = DBI->connect( 'dbi:Firebird...);
my $ora_sth = $ora_dbh->prepare(...);
my $fir_sth = $fir_dbh->prepare(...);
my $csv_sth = $csv_dbh->prepare("
        SELECT $cols
          FROM IMPORT(?) AS T1
  NATURAL JOIN IMPORT(?) AS T2 ...
");
$csv_sth->execute( $fir_sth, $ora_sth );

[download]
The syntax for the join must follow the SQL::Statement rules, while the two statement handles follow the syntax rules of the respective DBMSs they query.

In reply to Re: DBI sanity check by jZed
in thread DBI sanity check by mring

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.