Question

我有一个表my_table，其中的jsonb列包含一些数据，例如，在单行中，该列可以包含以下数据：

[
  {
    "x_id": "1",
    "type": "t1",
    "parts": [
       { "part_id": "1", price: 400 },
       { "part_id": "2", price: 500 },
       { "part_id": "3", price: 0 }
     ]
  },
  {
    "x_id": "2",
    "type": "t1",
    "parts": [
       { "part_id": "1", price: 1000 },
       { "part_id": "3", price: 60 }
     ]
  },
  {
    "x_id": "3",
    "type": "t2",
    "parts": [
       { "part_id": "1", price: 100 },
       { "part_id": "3", price: 780 },
       { "part_id": "2", price: 990 }
     ]
  }
]

我需要帮助，找到如何在给定parts和x_id的情况下从part_id数组中删除元素。

示例

鉴于x_id=2和part_id=1，我需要将数据更新为：

[
  {
    "x_id": "1",
    "type": "t1",
    "parts": [
       { "part_id": "1", price: 400 },
       { "part_id": "2", price: 500 },
       { "part_id": "3", price: 0 }
     ]
  },
  {
    "x_id": "2",
    "type": "t1",
    "parts": [
       { "part_id": "3", price: 60 }
     ]
  },
  {
    "x_id": "3",
    "type": "t2",
    "parts": [
       { "part_id": "1", price: 100 },
       { "part_id": "3", price: 780 },
       { "part_id": "2", price: 990 }
     ]
  }
]

PS1：无法对这些数据进行标准化，因此这不是可行的解决方案。

PS2：我正在运行PostgreSQL 9.6

PS3：我已经检查了this question和this question，但是与其他问题相比，我的数据结构似乎过于复杂，因此无法应用给出的答案。

Edit1 ：json数据可能很大，尤其是parts数组，该数组可以从少至0个元素到数千个元素。

Answer 1

这应该有效，只需要另一个唯一列（通常是主键）

创建测试表

create table test_tab(
id serial primary key,
j jsonb
);

insert into test_tab
(j)
values
('[
  {
    "x_id": "1",
    "type": "t1",
    "parts": [
       { "part_id": "1", "price": 400 },
       { "part_id": "2", "price": 500 },
       { "part_id": "3", "price": 0 }
     ]
  },
  {
    "x_id": "2",
    "type": "t1",
    "parts": [
       { "part_id": "1", "price": 1000 },
       { "part_id": "3", "price": 60 }
     ]
  },
  {
    "x_id": "3",
    "type": "t2",
    "parts": [
       { "part_id": "1", "price": 100 },
       { "part_id": "3", "price": 780 },
       { "part_id": "2", "price": 990 }
     ]
  }
]');

然后拆分json，过滤不必要的数据，然后再次重新创建json：

 select id, jsonb_agg( jsonb_build_object('x_id',xid, 'type',type, 'parts', case when inner_arr = '[null]'::jsonb  then parts_arr::jsonb else inner_arr  end) ) 
 from (
    select 
    id, 
     value->>'x_id' as xid, 
    jsonb_agg(inner_arr) as inner_arr,
    max(value->>'parts') as parts_arr,
    max(value->>'type') as type
    from (
        select * , 
        case when value->>'x_id'='2' then jsonb_array_elements(value->'parts')  else NULL end inner_arr 
        from test_tab
        join lateral jsonb_array_elements(j)
        on true
    ) t
    where
    inner_arr->>'part_id'  is distinct from '1'
    group by id, value->>'x_id' 
) t
group by id

Answer 2

我认为您可以使用#-运算符（请参阅functions-json），您只需要找到从以下位置删除数组元素的路径即可。

select
    data #- p.path
from test as t
    cross join lateral (
        select array[(a.i-1)::text,'parts',(b.i-1)::text]
        from jsonb_array_elements(t.data) with ordinality as a(data,i),
            jsonb_array_elements(a.data->'parts') with ordinality as b(data,i)
        where
            a.data ->> 'x_id' = '2' and
            b.data ->> 'part_id' = '1'
    ) as p(path)

或

update test as t set
    data = data #- (
        select
            array[(a.i-1)::text,'parts',(b.i-1)::text]
        from jsonb_array_elements(t.data) with ordinality as a(data,i),
            jsonb_array_elements(a.data->'parts') with ordinality as b(data,i)
        where
            a.data ->> 'x_id' = '2' and
            b.data ->> 'part_id' = '1'
    )

db<>fiddle demo

更新好吧，如果数据中不存在给定路径，则有一个合理的注释，即更新部分无法正常工作。我猜在这种情况下，您将在where子句中重复表达式：

update test as t set
    data = data #- (
        select
            array[(a.i-1)::text,'parts',(b.i-1)::text]
        from jsonb_array_elements(t.data) with ordinality as a(data,i),
            jsonb_array_elements(a.data->'parts') with ordinality as b(data,i)
        where
            a.data ->> 'x_id' = '2' and
            b.data ->> 'part_id' = '23222'
    )
where
    exists (
        select *
        from jsonb_array_elements(t.data) as a(data),
            jsonb_array_elements(a.data->'parts') as b(data)
        where
            a.data ->> 'x_id' = '2' and
            b.data ->> 'part_id' = '23222'
    )

db<>fiddle demo

或者您可以使用自我加入：

update test as t2 set
    data = t.data #- p.path
from test as t
    cross join lateral (
        select array[(a.i-1)::text,'parts',(b.i-1)::text]
        from jsonb_array_elements(t.data) with ordinality as a(data,i),
            jsonb_array_elements(a.data->'parts') with ordinality as b(data,i)
        where
            a.data ->> 'x_id' = '2' and
            b.data ->> 'part_id' = '23232'
    ) as p(path)
where
    t.ctid = t2.ctid

db<>fiddle demo

在jsonb列中深度嵌套的数组中删除元素-Postgres

2 个答案: