If you execute: 
$sth = $dbh->prepare('UPDATE sometable SET value1=? WHERE value2=?');
$sth->execute('something with \n in it', 'something else which inciden
+tally has a \n in it');

[download]
I'm quite sure that the SQL will receive the strings exactly as you supplied it (Otherwise database-users around the world will have to start worrying quite a bit).
In this case, using single-quotes, the \n will not be interpreted and supplied to the database as-is. If you want (perl) to interpret the \n and send a singular newline (0x0A), use double-quotes in the execute-statement.

However (using double-quotes), when you use \n in the WHERE-clause it will only match LF's (0x0A) and not CRLF (0x0D0A), should those be present. If you also want to match those, you should do this: 

$sth = $dbh->prepare('UPDATE sometable SET value1=? WHERE value2=? OR 
+value2=?');
$sth->execute("something with \n in it", "something else which inciden
+tally has a \n in it", "something else which incidentally has \r\n in
+ it");

[download]

In reply to Re^3: Line separators when passing multi-line fields to a database by Neighbour
in thread Line separators when passing multi-line fields to a database by davies

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.