必须出现在sql中的group by子句中

我有一个sql语句，我试图添加ORDERBY，当我添加order语句时，我得到一个错误

错误：列“items.id”必须出现在GROUP BY子句中或用于聚合函数中

我的问题是

WITH "has_children_cte" 
     AS (SELECT DISTINCT "parent_id" AS "item_id", 
                         1           AS "has_children" 
         FROM   "items") 
SELECT "item_category_id", 
       Count(*) AS "count" 
FROM   "items" 
       INNER JOIN "items" AS "root_item" 
               ON ( "root_item"."id" = "items"."root_id" ) 
       LEFT JOIN "item_types" 
              ON ( "items"."item_type_id" = "item_types"."id" ) 
       LEFT JOIN "item_categories" 
              ON ( "item_categories"."id" = "item_types"."item_category_id" ) 
       INNER JOIN "order_items" 
               ON ( "items"."order_item_id" = "order_items"."id" ) 
       INNER JOIN "orders" 
               ON ( "order_items"."order_id" = "orders"."id" ) 
       LEFT JOIN "has_children_cte" 
              ON ( "items"."id" = "has_children_cte"."item_id" ) 
WHERE  ( ( "items"."parent_id" IS NULL ) 
         AND ( "items"."state" != 'discarded' ) ) 
GROUP  BY "item_category_id" 
ORDER  BY "items"."id"; 

我已经按“项目”添加了

订单

然后我得到了这个错误。当我尝试将items.id添加到group by时，我得到了错误的结果

很遗憾，我无法处理此错误。
按

排序（逻辑上）发生在聚合之后。聚合后，

“项”。“id”

在每一行中都不可用

因此，只需使用聚合函数：

ORDER  BY MIN("items"."id")

为什么要按“项目”“id”订购？查询结果显示“类别id”和计数