度数据库报错-用php逐条读取mysql中的数据报错为什么？？

<code><?php    $con = mysql_connect("localhost:3306","root","123456") or die("数据库连接失败".mysql_error());    mysql_select_db("vote",$con) or die ("数据库选择失败".mysql_error());    mysql_query("set names utf8");    $a = mysql_query("select news from news");    $b = mysql_fetch_row($a);        while($b = mysql_fetch_row($a))        {            echo $b["0"].'<br>';            echo $b["1"].'<br>';        }?></code>

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