我有以下php代码:
$host="localhost"; // Host name
$username="***"; // username
$password="***"; // password
$db_name="***"; // Database name
//$rc_profile_table="rc_profile_table"; // Table name
//$rc_profile_relation_table="rc_profile_relation_table"; // Table name
mysql_connect("$host", "$username", "$password");
mysql_select_db("$db_name");
$sql="SELECT created_at FROM rc_profile_table where created_at > 2011-04-19 08:00:00";
$result=mysql_query($sql);
$count=mysql_num_rows($result);
$sql="SELECT created_at FROM rc_profile_relation_table where created_at > 2011-04-19 08:00:00";
$result2=mysql_query($sql);
$count2=mysql_num_rows($result);
mysql_close();
你到底想做什么?你必须把问题描述出来，否则没人能帮你。
没有正确的错误处理。php提供的mysql功能有一个内置函数，它在屏幕上输出错误。这样会好很多:
<?php
$host="localhost"; // Host name
$username="***"; // username
$password="***"; // password
$db_name="***"; //db name
$connection = mysql_connect($host, $username, $password) or die("Could not connect to the database: " . mysql_error());
mysql_select_db($db_name, $connection) or die("Could not select database: " . mysql_error());
$sql = "SELECT `created_at` FROM `rc_profile_table` WHERE `created_at` > '2011-04-19 08:00:00'";
$result = mysql_query($sql) or die("Could not execute query: " . $sql . "ERROR: " . mysql_error());
$count = mysql_num_rows($result);
mysql_close($connection) or die(mysql_error());
?>
除了前面提到的错误处理之外，对于第二个结果集，您可能希望确保$count2是在$result2中返回的行数，而不是在第一个结果集($result)
$sql="SELECT created_at FROM rc_profile_relation_table where created_at > 2011-04-19 08:00:00";
$result2=mysql_query($sql);
$count2=mysql_num_rows($result2);