问题描述
我在 SQL 中有一个表,其中有多个行用于同一 ID.
I have a table in SQL that has multiple lines for the same id.
例如:
ID event_id category_id 1 1 3 2 1 6 3 1 18 4 1 24 5 2 1
我想知道如何进行 SQL 查询来实现每个 event_id 的输出,它显示了它所在的所有类别.
I am wondering how I would make an SQL query to achieve the output for each event_id it shows all the categories it is in.
例如
{ "event_id": 1, "categories": [3, 6, 18, 24] }
谢谢
推荐答案
字符串聚合是否足够?
select event_id, string_agg(category_id, ',') within group (order by category_id) from t group by event_id;