Postgres JSON_AGG和Order By不合作

Question

我有一个如下所示的查询：

SELECT *,
(SELECT json_agg(deals.*) FROM deals WHERE vendors.id = deals.vendorid ORDER BY priority) as deals
FROM vendors

该查询效果很好，但是当我尝试通过error: column "deals.priority" must appear in the GROUP BY clause or be used in an aggregate function 表中的字段进行排序时，这样：

{{1}}

我收到以下错误：

{{1}}

任何想法如何做这样的事情？

Answer 1

语法不应该是这个吗？

(SELECT json_agg(deals.*) WITHIN GROUP (ORDER BY priority)
 FROM deals
 WHERE vendors.id = deals.vendorid 
) as deals

文档为here。

Answer 2

你可以

SELECT *,
(SELECT json_agg(deals.* ORDER BY priority) FROM deals WHERE vendors.id = deals.vendorid) as deals
FROM vendors

请参阅examples with array_agg and string_agg。