PHP (MySQL) error : “Warning: mysql_num_rows() expects parameter 1 to be resource” [duplicate]

Answer 1

$result is false because your query is invalid (has a syntax error). Use:

$sql = "UPDATE members SET conf=2 WHERE email = '$email_to';"

(note the quotes surrounding $email_to)

Also mysql_num_rows() should be used for SELECT queries only. For UPDATE, INSERT and DELETE, use mysql_affected_rows() instead.

Finally, for future reference, if your query doesn't work, print the error and the SQL query used (something like what's on Col Shrapnel's answer). It will help you know what's wrong.

Answer 2

$result=mysql_query($sql);

to

$result=mysql_query($sql) or trigger_error(mysql_error().$sql);

and run it again

and then

$email_to=$_POST['email_to'];

to

$email_to=mysql_real_escape_string($_POST['email_to']);

oh yes, and there is also quotes

Answer 3

The SQL you performed was not a SELECT, so no rows are returned!