I wanna check $username to make sure that it only contains letters and numbers and a underscore, anythig else giver error(); 
error() unless $username =~ m< ^ \w+ \z >x;

[download]
Is there in way in SQL to select a row by random, so if it havd 1000 rows it picked row 200.
There isn't a generic way to pick a random row in MySQL, but if you've got a primary key which is an integer and you know the amount of rows you've got then you can just pick a random number and SELECT from that e.g 
my $sth = $dbh->prepare(
               'SELECT some,rows FROM your_table WHERE id = ?'
          );
$sth->execute( 
    int rand $dbh->selectrow_array('SELECT MAX(*) FROM your_table')
);

[download]

HTH

_________
broquaint

update: changed COUNT to MAX (thanks to UnderMine for that one)

In reply to Re: Username regex, MYSQL random by broquaint
in thread Username regex, MYSQL random by Anonymous Monk

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.