php - Rate system warning mysql_fetch_assoc? -

hi i'm kind of beginner , not know how solve problem. i'm trying create rate system. got done there problem , not know how proceed. assistance thank you.

here's code:

<?php     $query = mysql_query("select * hry");      while($data = mysql_fetch_assoc($query)){         $rate_db[] = $data;         $sum_rates[] = $data['rate'];     }     if(@count($rate_db)){         $rate_times = count($rate_db);         $sum_rates = array_sum($sum_rates);         $rate_value = $sum_rates/$rate_times;         $rate_bg = (($rate_value)/5)*100;     }else{         $rate_times = 0;         $rate_value = 0;         $rate_bg = 0;     } ?> 

here's error:

warning: mysql_fetch_assoc () expects parameter 1 resource, boolean given  in /data/web/virtuals/88892/virtual/www/domains/viveregames.cz/pohledy/clanek.phtml   on line 28 

error means query failed.

because when query fails, mysql_query() returns false , false, think know, boolean..

well, using mysql syntax deprecated.

i suggest use pdo or mysqli.

also don't see connections database...

if aren't connected db, mysql_query returns false.

then, code shown completed? or missing things connection, select db , others?

if answer question yes then:

add these simple code lines before actual code:

$conn = mysql_connect('localhost', 'username', 'password');  if (!$conn) {     die ('error while attempting connection db: ' . mysql_error()); }  $db_selected = mysql_select_db('test', $conn); if (!$db_selected) {     die ("error while selecting db: " . mysql_error()); } 

if answer question no, please edit post adding code lines.