mysql_num_rows使用

 include("onn.php");$query=mysql_query('select * from book');$num=mysql_num_rows($query/)/这里是把query的执行结果代入mysql_num_row语句中echo $num;for($i=0;$i<$num;$i++){$sql='UPDATE `db_borrow`.`tb_bookinfo` SET `id` = '."'".$i."'".' WHERE `book`.`id` = '."'".$i."'";echo $sql."<br>";mysql_query($sql);}