Question

I'm trying to select the top 5 results, but whenever adding order by votes desc limit 5 to this code:

$req2 = mysql_query('select id, url, name, description, banner, votes 
                     from topsite 
                     order by votes desc 
                     limit '.$first_message .','.$last_message); 
while($dnn2 = mysql_fetch_array($req2))

it won't work. How can I fix it?

Answer 1

如果你只想要TOP 5那么你只需要一个像这样的限制器

此外，如果您在查询周围使用双引号，则可以自动展开$variables，这样可以更轻松地进行阅读和调试。

此外，如果您想查看mysql_扩展程序产生的错误，您必须查找它们

$top_5_please = 5;

$req2 = mysql_query("select id, url, name, description, banner, votes 
                     from topsite 
                     order by votes desc 
                     limit $top_5_please"); 

// error check
if ( ! $req2 ) {
    echo mysql_error();
    exit;
}

while($dnn2 = mysql_fetch_array($req2))

最终注释

请不要使用mysql_数据库扩展，不推荐使用（在PHP7中永远消失）特别是如果您只是学习PHP，请花时间学习PDO或mysqli_数据库扩展， and here is some help to decide which to use

Answer 2

您可以尝试以下操作。另请注意，不推荐使用mysql_ *函数。请改用PDO。

$req2 = mysql_query('select id, url, name, description, banner, votes 
                     from topsite 
                     order by votes desc 
                     limit '.$your_limit .' OFFSET '.$your_offset);

Answer 3

[{ "prefix.age": 1, "prefix.name": "Apple" }]

你不能将字符串传递给限制你只能在限制

中使用整数

Select top 5 results: PHP/SQL

3 个答案: