json - 汇总 JSON 值

Question

有什么方法可以让我从列中读取 json 数据并根据它们的键将值加在一起并排列它们。该列的示例是:

id_column | json_data
1         | {"A": 1, "C": 4, "D": -2}
2         | {"B": 3, "S": 0, "A": 2, "D": 0}

我想要得到的最终结果应该是这样的:

json_data
{"A": 3, "B": 3, "C": 4, "D": -2, "S": 0}

所以最终的结果其实就是每一行的json数据的总和，而且key是按照A-Z的顺序排列的。

Answer 1

这将按如下方式工作:

SELECT json_object_agg(key, val ORDER BY key)
FROM (SELECT t.key,
             sum(CAST(t.val AS bigint)) AS val
      FROM j
         CROSS JOIN LATERAL jsonb_each_text(j.json_data)
                            AS t(key, val)
      GROUP BY t.key
     ) AS q;

                 json_object_agg                  
--------------------------------------------------
 { "A" : 3, "B" : 3, "C" : 4, "D" : -2, "S" : 0 }
(1 row)

jsonb中没有顺序，所以我用json作为结果。