Magnetic Monks, I've used 'undef' like this:

while ($data = $sth->fetchrow_array()) {
    $hash{$data} = undef;
}
[download]

But I was wondering if there's an opportunity to use it to improve the efficiency of queries like this:

$sql = 'SELECT col_1 FROM theTable';
.....
while ($data = $sty->fetchrow_array()) {
    push @my_list, $data;
}
[download]

or

$sql = 'SELECT col_1, col_2, col_3, col_4, col_5 FROM theTable';
.....
while (@data = $sty->fetchrow_array()) {
    $my_hash{$data[0]} = [ $data[1], $data[2], $data[3], $data[4] ];
}
[download]

Thanks.

---

In reply to How to use undef in DBI sql query result collection by punch_card_don

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! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

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:
	&		&
	<		&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.