Question

我有此数据：

 invid |            contents             
-------+---------------------------------
   109 | {"49": {"22000.00": "10.00"}}
   108 | {"49": {"22000.00": "312.00"}}
   106 | {"48": {"50000.00": "20.00"}}
   103 | {"50": {"1020000.00": "20.00"}}
   102 | {"48": {"50500.00": "20.00"}}
   101 | {"52": {"30060000.00": "0.00"}}
    89 | {"50": {"1020000.00": "2.00"}}
    88 | {"48": {"50000.00": "20.00"}}
    87 | {"50": {"1020000.00": "1.00"}}
    86 | {"50": {"10020000.00": "3.00"}}
    83 | {"48": {"50000.00": "30.00"}}
    82 | {"50": {"1020000.00": "4.00"}}
    81 | {"47": {"20000.00": "40.00"}}
    80 | {"48": {"50000.00": "200.00"}}
    79 | {"50": {"1020000.00": "20.00"}}

我想要结果：

[{50:5,48:4,49:3,52:1,47:1}]

或

[{'50':5,'48':4,'49':3,'52':1,'47':1}]

降序。

Answer 1

您需要提取所有键并将结果分组：

select ky, count(*) as numkeys
from data
   cross join lateral jsonb_object_keys(contents) as t(ky)
group by ky
order by ky;

如果您想要一个带有结果的JSON数组，则可以使用jsonb_object_agg()：

select jsonb_object_agg(ky, numkeys) 
from (
  select ky, count(*) as numkeys
  from data
    cross join lateral jsonb_object_keys(contents) as t(ky)
  group by ky
  order by ky
) t;

在线示例：https://rextester.com/HDB83302

我想从Postgres中的json数据中获取最大密钥数

1 个答案: