unf... mi mnogo qsno che shte ti vrashta invalid query. Nqmash tablica "table" i zatfa...
Ok... znachi shte se opitam da go napravq konkretno za tvoq sluchaj:

// tfa go promenqsh kakto trqbva da e
$TableName = 'mytable';
$mysql_user = 'user';
$mysql_pass = 'pass';
$mysql_db = 'db';
$mysql_host = 'localhost';

$email = 'moq@email.com';

$hServer = mysql_connect($mysql_host,$mysql_user,$mysql_pass) or die("Cannot connect to server");
$Result = mysql_select_db($mysql_db) or die(mysql_error($hServer));

$Query = "select usId from $TableName where email='$email'";
$Result = mysql_query($Query) or die (mysql_error($hServer));
$num_rows = mysql_num_rows($Result);

echo "Broj redove: $num_rows";
mysql_close($hServer);