MySQL列数据以逗号分隔列表返回 [英] MySQL column data returned as comma delimited list

问题描述

我目前有一个MySQL表，例如:

I currently have a MySQL table like:

id | friend
1  |   2
1  |   5
1  |   10
3  |   6
15 |   19
21 |   4

我正在尝试获取一个特定用户的所有朋友ID，并将其排列成逗号分隔的列表.例如，抓住user1的朋友，它将返回为

I'm trying to grab all the friend id's of one particular user and arrange them into a comma-delimited list. For example, grabbed user1's friends, it would return as

$friend_list = 2,5,10

当前，我有:

$sql = "SELECT friend FROM table__friends WHERE id = ".$user_id;

这只能抓一行..请帮助！

This only grabs one row though..please help!

谢谢

推荐答案

您要使用GROUP_CONCAT:

You want to use GROUP_CONCAT :

$sql = "SELECT GROUP_CONCAT(friend) FROM table__friends GROUP BY id HAVING id = ".$user_id;

根据更好的答案进行正确性调整.

Adjusted for correctness per the better answer.

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