Postgres JSON_AGG 和 Order By 不一起工作

Question

我有一个看起来像这样的查询：

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

该查询效果很好，但是当我尝试按deals表中的字段进行排序时，如下所示：

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

我收到以下错误：

error: column "deals.priority" must appear in the GROUP BY clause or be used in an aggregate function

任何想法如何做这样的排序？

Answer 1

你可以

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

请参阅带有array_agg和 的示例string_agg。

Answer 2

语法不应该是这样吗？

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

文档在这里。