pgsql 字符串转数组关联其他表，匹配 拼接后原顺序展示

实现原理：

1.unnest(string_to_array(mnc.email_user_id , ','))字符串转数组 在转成行然后进行匹配

2.WITH ORDINALITY a(user_id, nr)此函数用于显示下标，便于后边排序

3.匹配后按原顺序聚合即可

源数据如下图红框中

 想要实现的效果如下（顺序一致）

 实现的sql如下

select
	string_agg(b.user_name || '(' || b.user_id || ')', ',')as emailUserName ,
	b.email_user_id
from
	(
	select
		su.user_name,
		su.user_id ,
		mnc.*
	from
		fas_mail_notification_config mnc,
		unnest(string_to_array(mnc.email_user_id , ','))with ordinality a(user_id,nr)
	left join sec_user su on a.user_id = su.user_id
	where
		mnc.delete_flg = 0
		and mnc.bg_id = '49bd50924c434556aca0193bcffb2dce'
		and mnc.business_type = '1'
	order by
		mnc.id,
		mnc.bg_id ,
		a.nr
      )b
group by
	b.id,
	b.bg_id,
	b.email_user_id