Table of Contents for

MySQL in a Nutshell, 2nd Edition

This function returns the number of rows affected by a previous SQL statement that modified rows of data for the current MySQL session. The function returns –1 if the previous statement failed. It works only after INSERT, UPDATE, and DELETE statements. See mysql_num_rows() later in this section for the number of rows returned by a SELECT statement. The connection identifier may be given as an argument to retrieve the number of rows affected by a different connection. Here is an example:

...
$sql_stmnt = "UPDATE workreq
              SET due_date = ADDDATE(due_date, INTERVAL 1 DAY)
              WHERE due_date = '2004-07-28'";
mysql_query($sql_stmnt);
$updated = mysql_affected_rows( );
print "Number of Rows Updated:  $updated \n";
...

This script changes the due dates for all work requests by one day.