请问一个查询数据库输出后进行判断的有关问题

请教一个查询数据库输出后进行判断的问题！

<br>
<!--?php<br /-->
<br>
$mysql_server_name='localhost';<br>
$mysql_username='root';<br>
$mysql_password='123456';<br>
$mysql_database='you';<br>
<br>
$conn = mysql_connect($mysql_server_name,$mysql_username,$mysql_password);<br>
<br>
mysql_select_db($mysql_database,$conn);<br>
<br>
mysql_query("set names 'utf8'");<br>
<br>
$sql = "SELECT * FROM `member` WHERE username LIKE 'xiha'";<br>
<br>
$result = mysql_query($sql,$conn);<br>
<br>
$row = mysql_fetch_array($result);<br>
<br>
mysql_close($conn); <br>
<br>
if($row['groupid'] = '1'){<br>
        $capacity = '100';<br>
} else if($row['groupid'] = '10'){<br>
        $capacity = '1000';<br>
} else {<br>
        exit();<br>
}<br>
<br>
echo $capacity;<br>
<br>
?><br>

数据库格式为：

uid username groupid
1 haha 1
2 xiha 10

用if elseif 判断时：
输出的$capacity 始终是第一次的判断的值 100
if($row['groupid'] = '1'){
$capacity = '100';
}


------解决方案--------------------
if($row['groupid'] == '1'){

一个 = 是赋值
两个才是比较