Questions about php query in MYsql?

Question about php query in MYsql ?? I want to query the corresponding value based on a specific value in the data. for example, the user value is known and the pwd value is displayed. The code I tested in phpamdin is: $ SQL & nbsp; SELECT & nbsp; pwd & nbsp; & nbsp ;. & nbsp; FROM & php query problems in MYsql ??
I want to query the corresponding value based on a specific value in the data. for example, the user value is known and the pwd value is displayed. The code I tested in phpamdin is:

$sql = 'SELECT pwd'
        . ' FROM `appdata` '
        . ' WHERE user = \'jimmy@qq.com\' LIMIT 0, 30';

However, the execution in the PHP file is always unsuccessful.

The following is my code. how can I modify it?

     include_once "logindatabase.php";
    $cmd = mysql_query(SELECT * FROM appdata WHERE user =jimmy@qq.com);
    $rec = mysql_fetch_array($cmd);
    echo $rec[Pwd];
?>

Thank you ~
------ Solution --------------------
Include_once "logindatabase. php ";
$ Cmd = mysql_query ('select * FROM appdata WHERE user = "jimmy@qq.com "');
$ Rec = mysql_fetch_array ($ cmd );
// While ($ rec = mysql_fetch_array ($ cmd ))
Echo $ rec ['pwd'];
?>