请教一个查询数据库输出后进行判断的问题！

<?php

$mysql_server_name='localhost';
$mysql_username='root';
$mysql_password='123456';
$mysql_database='you';

$conn = mysql_connect($mysql_server_name,$mysql_username,$mysql_password);

mysql_select_db($mysql_database,$conn);

mysql_query("set names 'utf8'");

$sql = "SELECT * FROM `member` WHERE username LIKE 'xiha'";

$result = mysql_query($sql,$conn);

$row = mysql_fetch_array($result);

mysql_close($conn); 

if($row['groupid'] = '1'){
        $capacity = '100';
} else if($row['groupid'] = '10'){
        $capacity = '1000';
} else {
        exit();
}

echo $capacity;

?>

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';
}


[解决办法]
if($row['groupid'] == '1'){

一个 = 是赋值
两个才是比较