mysql查询mysql_num_rows无法正常工作

Question

以下是示例代码。请帮助我。

$query=mysql_query("set @row_count=0;SELECT *,@row_count := @row_count+1 as rank FROM users WHERE username='$username' ");
$numrows=mysql_num_rows($query);

Answer 1

只需使用：

$query=mysql_query("SELECT * , count(*) as rank FROM users WHERE username='$username' ");
$numrows=mysql_num_rows($query);

Answer 2

在执行ROW_NUMBER()功能时尝试另一种方式。见下文：

$query=mysql_query("SELECT @row_count:=@row_count+1 AS rank, * FROM users, (SELECT @row_count:=0) AS A WHERE username='$username'");
$numrows=mysql_num_rows($query);