sql - mysql_num_rows 错误

Question

不知道问题出在哪里!

$msgs = mysql_num_rows(mysql_query("SELECT * FROM messages WHERE recipient = $userID AND read = 0"));


echo $msgs;

如果我删除“and read =0”，上面的代码就可以工作。但如果不是我得到:

Warning: mysql_num_rows(): supplied argument is not a valid MySQL result resource in left_menu.php on line 16

.

I have a field in the table called read (tinyint 1,defualt 0)

CREATE TABLE IF NOT EXISTS `messages` (
`id` int(10) unsigned NOT NULL AUTO_INCREMENT,
`sender` int(10) unsigned NOT NULL DEFAULT '0',
`recipient` int(10) unsigned NOT NULL DEFAULT '0',
`subject` varchar(255) CHARACTER SET utf8 NOT NULL,
`message` text CHARACTER SET utf8,
`date` int(10) unsigned NOT NULL DEFAULT '0',
`read` tinyint(1) NOT NULL DEFAULT '0',
PRIMARY KEY (`id`)
)

INSERT INTO `messages` (`id`, `sender`, `recipient`, `subject`, `message`, `date`, `read`) VALUES
(1, 47, 13, 'Hello!', 'TEST!', 1228326055, 0),
(2, 536, 13, 'blblabla', 'yeah', 1248506708, 0);

有什么问题吗？

Answer 1

read 是保留关键字，因此这会生成 MySQL 语法错误。但是，在 MySQL 提示符下，这是有效的:

SELECT * FROM messages WHERE recipient = 1 AND `read` = 0;

您必须在 PHP 查询中对其进行反引号。