PHP and MySQL for Dynamic Web Sites: Visual QuickPro Guide

Using mysql_num_rows()

The next logical function to discuss is mysql_num_rows(). This function returns the number of rows retrieved by a SELECT query, taking the query result as a parameter.

I’ll use this function in two different ways. First I’ll modify view_users.php to list the total number of registered users. Second, I’ll modify register.php to test if a username has already been taken.

To modify view_users.php:

1.	Open view_users.php (refer to Script 6.7) in your text editor.
2.	Before the if ($result) conditional (line 12), add this line (Script 6.9) $num = mysql_num_rows ($result); This line will assign the number of returned rows to the $num variable.
3.	Change the original $result conditional to if ($num > 0) { The conditional ...