Chyba mysql_fetch_assoc() expects parameter 1 to be resource

Warning: mysql_fetch_assoc() expects parameter 1 to be resource, boolean given in /home/users/nick/adresa.cz/web/index.php on line 62 

mysql_fetch_assoc() expects parameter 1 to be resource, boolean given in /home/users/nick/adresa.cz/web/index.php on line 93 

<?php
        $novinky=mysql_query("SELECT datum,nadpis,text FROM novinky ORDER BY id DESC LIMIT 2");
        while($n=mysql_fetch_assoc($novinky)){
          echo '<div class="novinka">'."\n";
          echo '<h3>'.$n['nadpis'].' <span class="datum">'.$n['datum'].'</span></h3>'."\n";
          echo '<p>'.$n['text'].'</p>'."\n";
          echo "</div>\n";
        }
        ?>

<?php
      $vyherci=mysql_query("SELECT vyhra,jmeno,cislo,vyhra_cele FROM vyherci ORDER BY id DESC LIMIT 5");
      while($v=mysql_fetch_assoc($vyherci)){
        echo '<div class="vyherce">'."\n";
        echo '<p>'.$v['jmeno'].'</p>'."\n";
        echo '<p><img src="/obr/aukce/male/'.$v['vyhra'].'.png" alt="'.$v['vyhra_cele'].'" title="'.$v['vyhra_cele'].'"></p>'."\n";
        echo '<div class="infobox">'."\n";
        echo '<p class="prvni">Za <span class="vetsi">1 SMS</span></p>'."\n";
        echo '<p>'.$v['cislo'].'</p>'."\n";
        echo "</div>\n";
        echo "</div>\n";
      }