sql - Postgresql根据其JSONB字段值总和更新记录列

Question

我在 Postgresql 9.6.5 中有一个表，其中包含一些字段，例如:

CREATE TABLE test (
  id SERIAL,
  data JSONB,
  amount DOUBLE PRECESION,
  PRIMARY KEY(id)
);

在data列中有像这样的json对象:

{
"Type": 1,
  "CheckClose":
    {"Payments":
      [
        {"Type": 4, "Amount": 2068.07},
        {"Type": 1, "Amount": 1421.07}
      ]
    }
}

我需要做的是将Payments字段的Amount值的总和放入每行的amount字段中 >数据对象。例如，对于此特定对象，应为 2068.07 + 1421.07 = 3489.14。 我读过一些关于 Postgres json 和 jsonb 函数的内容，所以我现在在这里:

UPDATE test SET amount=sum((jsonb_array_elements(data::jsonb->'CheckClose'->'Payments')->>'Amount')::FLOAT)

这不起作用 - 我收到有关在 UPDATE 中未使用聚合函数的错误。

我尝试这样做:

UPDATE test SET amount=temp.sum
  FROM (
     SELECT sum((jsonb_array_elements(data::jsonb->'CheckClose'->'Payments')->>'Amount')::FLOAT) AS "sum"
    FROM test WHERE id=test.id
  ) as "temp"

现在我收到错误在上下文中调用的集值函数无法接受集合

我应该怎么做？我只需要计算总和并将其放入另一行，这是一项艰巨的任务吗？ 请任何人帮我解决这个问题。谢谢。

Answer 1

返回 fn() 聚合的集合尝试:

t=# with c(j) as (values('{"Payments":
      [
        {"Type": 4, "Amount": 2068.07},
        {"Type": 1, "Amount": 1421.07}
      ]
    }'::jsonb))
select sum((jsonb_array_elements(j->'Payments')->>'Amount')::float) from c;

错误:

ERROR:  aggregate function calls cannot contain set-returning function calls
LINE 7: select sum((jsonb_array_elements(j->'Payments')->>'Amount'):...
                    ^
HINT:  You might be able to move the set-returning function into a LATERAL FROM item.

很容易被另一个 cte 克服:

t=# with c(j) as (values('{"Payments":
      [
        {"Type": 4, "Amount": 2068.07},
        {"Type": 1, "Amount": 1421.07}
      ]
    }'::jsonb))
, a as (select (jsonb_array_elements(j->'Payments')->>'Amount')::float am from c)
select sum(am) from a;
   sum
---------
 3489.14
(1 row)

所以现在只需从 CTE 更新:

with s as (SELECT ((jsonb_array_elements(data::jsonb->'CheckClose'->'Payments')->>'Amount')::FLOAT) AS "sm", id
    FROM test
)
, a as (select sum(sm), id from s group by id)
UPDATE test SET amount = sum
FROM a
WHERE id=test.id