连接到 MySQL 数据库并计算行数

发布于 2024-09-05 21:36:35 字数 476 浏览 6 评论 0原文

我需要连接到 MySQL 数据库，然后显示行数。这就是我到目前为止所得到的；

    <?php

include "connect.php";


db_connect(); 

$result = mysql_query("SELECT * FROM hacker"); 
$num_rows = mysql_num_rows($result); 


echo $num_rows; 

?>

当我使用该代码时，我最终出现此错误；

Warning: mysql_num_rows(): supplied argument is not a valid MySQL result resource in C:\Documents and Settings\username\Desktop\xammp\htdocs\news2\results.php on line 10

预先感谢：D

原文

I need to connect to a MySQL database and then show the number of rows. This is what I've got so far;

    <?php

include "connect.php";


db_connect(); 

$result = mysql_query("SELECT * FROM hacker"); 
$num_rows = mysql_num_rows($result); 


echo $num_rows; 

?>

When I use that code I end up with this error;

Warning: mysql_num_rows(): supplied argument is not a valid MySQL result resource in C:\Documents and Settings\username\Desktop\xammp\htdocs\news2\results.php on line 10

Thanks in advance :D

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傲鸠 2024-09-12 21:36:36

养成以这种方式运行所有查询的习惯：

$sql   = "SELECT * FROM hacker";
$res   = mysql_query($query) or trigger_error(mysql_error().$sql);

您将始终获得全面的错误信息
并采取适当的更正

，正如上面提到的，计算行数的唯一可靠方法是 SELECT count(*) 查询

$sql   = "SELECT count(*) FROM hacker";
$res   = mysql_query($query) or trigger_error(mysql_error().$sql);
$row   = mysql_fetch_row($res);
$count = $row[0];

take a habit to run all queries this way:

$sql   = "SELECT * FROM hacker";
$res   = mysql_query($query) or trigger_error(mysql_error().$sql);

and you will always have comprehensive error information
and take appropriate corrections

also, as it was mentioned above, the only reliable way to count rows is SELECT count(*) query

$sql   = "SELECT count(*) FROM hacker";
$res   = mysql_query($query) or trigger_error(mysql_error().$sql);
$row   = mysql_fetch_row($res);
$count = $row[0];

回复收藏 0 原文

浮生未歇 2024-09-12 21:36:36

更改您的代码如下：

$result = mysql_query("SELECT * FROM hacker");
echo mysql_error();

您有 SQL 错误或未连接到数据库

change your code as following:

$result = mysql_query("SELECT * FROM hacker");
echo mysql_error();

You have an SQL-Error or your not connected to the database

回复收藏 0 原文

感情洁癖 2024-09-12 21:36:35

您可能最好要求数据库聚合行数，而不是将它们全部传输到 php 并在那里进行计数。

SELECT COUNT(*) FROM hacker

You would probably be better of asking the database to aggregate the number of rows instead of transferring them all to php and doing the counting there.