如何从数据库中获取逗号分隔的值 [英] How to get comma separated values from database

问题描述

我有以下mysqli查询，我想让输出的数组变成(1,2,3,4)类型格式.

I have the following mysqli query, and I want to implode the array that's outputted into a (1,2,3,4) type format.

这是查询和asoc数组代码:

Here's the query and the asoc array code:

$user_categories = mysqli_query($connect, "SELECT sub_cat FROM subscriptions WHERE sub_user_id = '$user_id'");

$category_ids = mysqli_fetch_all($user_categories,MYSQLI_NUM);

print_r($category_ids);

$category_ids = implode(", ",$category_ids);

然后我得到以下输出，但似乎无法隔离这些值...

I then get the following output, and I can't seem to isolate the values...

Array ( 
[0] => Array ( [0] => 5 ) 
[1] => Array ( [0] => 8 ) 
[2] => Array ( [0] => 4 ) 
[3] => Array ( [0] => 2 ) 
)

很抱歉，如果我在这里确实遗漏了一些明显的内容.我一直在尝试修复此问题，由于缺乏PHP经验，我不确定100％确定要搜索什么.

Apologies if I'm missing something really obvious here. I've been trying to fix this for a while, and due to my lack of PHP experience, I'm not 100% sure what to search for.

我还尝试使用 $ user_categories 查询的结果进行一次简单的内爆，按照我在该主题上看到的其他StackExchange答案的说明进行操作，但一无所获(以下代码):

I've also tried a simple implode using the results of the $user_categories query, following the instructions of other StackExchange answers I've seen on the topic, but got nothing (code below):

$user_categories = mysqli_query($connect, "SELECT sub_cat FROM subscriptions WHERE sub_user_id = '$user_id'");

$category_ids = implode(", ",$user_categories);

echo $category_ids;

推荐答案

$ category_ids 是一个数组数组(行)，因此您不能只对其进行内爆.您需要从每一行获取第一个值并将其内爆.

$category_ids is an array of arrays (rows), so you can't just implode it. You need to fetch the first value from each row and implode that.

使用 array_column() :

$category_ids = implode(', ', array_column($category_ids, 0));

echo $category_ids;

输出:

5、8、4、2

5, 8, 4, 2

PHP 5.3+解决方案:

用 array_map() 代替 array_column() :

$category_ids = implode(', ', array_map(function ($row) { return $row[0]; }, $category_ids));

echo $category_ids;

输出:

5、8、4、2

5, 8, 4, 2

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