警告:mysql_num_rows()期望参数1为给定的资源布尔值 [英] Warning: mysql_num_rows() expects parameter 1 to be resource boolean given

问题描述

我刚刚将站点更改为新服务器，现在此代码出现错误:

I've just changed a site over to a new server, and now I'm getting an error with this code:

<?php 
    $result = mysql_query("SELECT * FROM trends ");
    $num_rows = mysql_num_rows($result);
    echo "<strong>" . $num_rows . "</strong>";
?>

错误是:

警告:mysql_num_rows()期望参数1为资源，给定布尔值.

Warning: mysql_num_rows() expects parameter 1 to be resource, boolean given.

我该如何解决?

干杯.

推荐答案

如果mysql_query失败，则返回false.

Your mysql_query return false if it fails.

对于SELECT，SHOW，DESCRIBE，EXPLAIN和其他返回的语句 结果集，mysql_query()成功返回资源，否则返回FALSE 错误."( http://php.net/manual/en/function.mysql -query.php )

"For SELECT, SHOW, DESCRIBE, EXPLAIN and other statements returning resultset, mysql_query() returns a resource on success, or FALSE on error." (http://php.net/manual/en/function.mysql-query.php)

因此，在使用结果之前，您需要检查查询是否失败(在这种情况下).

Therefore you need to check if the query failed (which is the case here) before using the result.

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