请问php 使用mysql_query时遇到的奇怪有关问题

<br />$uid='6';<br />$result = mysql_query("SELECT * FROM user WHERE uid='$uid'")<br />    or die("Invalid query: " . mysql_error());<br />print_r(fetch_array($result));<br />

<br />$username='匿名';<br />$resultt = mysql_query("SELECT * FROM user WHERE username='$username'")<br />    or die("Invalid query: " . mysql_error());<br />print_r(fetch_array($resultt));<br />

echo $resultt = mysql_query("SELECT * FROM user WHERE username='$username'")    or die("Invalid query: " . mysql_error());