How to know if MySQL returns 0

When I run this query `

SELECT id FROM bckoff WHERE left = 3;

` in phpmyAdmin, I get the correct response

MySQL returned an empty result set (i.e. zero rows).

H开发者_如何学Cowever, when I run the same query through my PHP code using mysql_query('the above query').. then I get "Resource ID#5" or "Resource ID#6" and so on..

How do I get the empty result set (or zero rows) in PHP ?

mysql_num_rows is the answer. This function returns the number of rows affected by a executed query.

$query = "SELECT id FROM bckoff WHERE left  = 3";

$result = mysql_query($query);

echo mysql_num_rows($result);

When you execute mysql_query($query) it executes the query and puts it in a resource. This resource can be read by different mysql-functions (like mysql_num_rows). For a complete overview of all MySQL functions have a look at http://nl.php.net/manual/en/ref.mysql.php

Note: Extension used in above code is deprecated as of PHP 5.5.0, Use MySQLi or PDO_MySQL extension. So instead of mysql_num_rows use mysqli_num_rows()

You can use mysql_num_rows function as:

$result = mysql_query("SELECT id FROM bckoff WHERE left = 3");
$num_rows = mysql_num_rows($result);
// $num_rows will be 0.

You need to use a mysql_fetch_* function to retrieve the results. Look here

Mysql Fetch Functions

There is a mysql_num_rows function that you can call on the $result returned by mysql_query("SELECT ...").

You might look into the MySQLi extension instead. It's a big improvement over the MySQL driver, and allows you to use prepared statements and bind parameters among other things, and I find it much more comfortable to use. You can look at the examples on the documentation page for num_rows.