You also have an internal set of quotes on the second SQL statement. Here's a better solution: 
$dbh->do(q{
    INSERT INTO test_db VALUES (?,?,?,?,?)
} undef, @fields);

[download]
That's lifted straight out of the Perl DBI book. Not only do you need to pass values to fill in placeholders as list elements, you don't need an extra set of quotes when you use the q// operator. They're implied.

Here's what I think you might have been trying to do:

my $sql = q{INSERT INTO test_db VALUES(} . join(', ', (undef, @fields)). ')';

In reply to RE: DBI:CSV problem by chromatic
in thread DBI:CSV problem by todd

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.