my $sth = $dbh->prepare("SELECT * FROM foo");
$sth->execute();

while (my $row = $sth->fetchrow_arrayref())
{
     # Use @$row like $row->[0], $row->[1], etc.
}
$sth->finish();    # Important!
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my $rows = $dbh->selectall_arrayref("SELECT * FROM foo");

# Now @$rows contains all the row data.
# Use @$rows like $rows->[$row_number]->[$column_number]...
foreach my $row (@$rows)
{
     # ...or @$row like $row->[$column_number]
}

# Repeat as required, as long as $rows is still defined.

# $sth->finish();  # Update per pope (Not required, no $sth defined)
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finish() is not necessary here, since all rows have been fetched. This is necessary in a case where after fetching particular rows, you want to discard the rest.

Rather than fetch the data a row at a time using $sth->fetchrow, you might fetch all of the data ahead of time, with something like $sth->fetchall_arrayref. Then you can do pretty much whatever you like with them.

If the data are too large to fit comfortably in memory, this isn't the right approach. In that case, you're probably better off doing multiple queries (if you prepare the query ahead of time using $dbh->prepare, you may save some time over doing a $dbh->query every time).

Update: D'oh! That's fetchall_arrayref, not fetchrow_arrayref. Thanks pope and Flexx!

--
F o x t r o t U n i f o r m
Found a typo in this node? /msg me
The hell with paco, vote for Erudil!

fetchrow_arrayref() also fetches a row at a time, it differs from fetchrow() only in the way it stores the return value. fetchrow() returns an array while fetchrow_arrayref() returns an array ref.

fetchall_arrayref() or fetchall_hashref() (quite new) would slurp in all at once.

use Data::Dumper;

...

$rows = $dbh->selectall_arrayref("SELECT ...");
# the first row:
print Dumper $rows->[0];
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Update: fixed typo