过滤存储在CLOB字段中的Json列表中的Json(Oracle DB)

3wabscal  于 2023-04-29  发布在  Oracle
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我一直在尝试修改Oracle DB中的CLOB字段(出于性能原因),该字段存储了一个JSON数组。
考虑这个微不足道的例子

+----+-----+------------------------------------------------------------------------------------------------------------------------------------+
| ID | COL |                                                                Json                                                                |
+----+-----+------------------------------------------------------------------------------------------------------------------------------------+
| 10 |  12 | [{"id":4, "name":"Jhon", age:40, opinion:null},{"id":3, name:"Jane", age:7},{"id":7, "name":"Peter", age:12, opinion:"somevalue"}] |
| 20 |  27 | [{"id":10, "name":"Julian", age:40, opinion:"somevalue"}]                                                                          |
| 30 |  40 | [{"id":30, "name":"Paul", age:20, opinion:"opinion"},{"id":3, name:"Jane", age:7}]                                                 |
+----+-----+------------------------------------------------------------------------------------------------------------------------------------+

我的目标是获得一个表,其中必须根据条件过滤Json列(它是一个CLOB,因为它可能非常大)。在这个例子中,假设条件是删除所有带有opinion = "somevalue"的json。结果将是:

+----+-----+------------------------------------------------------------------------------------+
| ID | COL |                                        Json                                        |
+----+-----+------------------------------------------------------------------------------------+
| 10 |  12 | [{"id":4, "name":"Jhon", age:40, opinion:null},{"id":3, name:"Jane", age:7}]       |
| 20 |  27 | []                                                                                 |
| 30 |  40 | [{"id":30, "name":"Paul", age:20, opinion:"opinion"},{"id":3, name:"Jane", age:7}] |
+----+-----+------------------------------------------------------------------------------------+

我的尝试:

我尝试使用JSON_ARRAYAGG函数来解决这个问题,但它不起作用。我的意思是,它的工作原理假设我不限制查询到一个特定的id。这是查询:

UPDATE table t SET t.JSON = (SELECT JSON_ARRAYAGG(
      JSON_OBJECT(
        'id' VALUE jt.id,
        'opinion' VALUE jt.opinion,
        'age' VALUE jt.age,
        'name' VALUE jt.name
      ) RETURNING CLOB )
FROM JSON_TABLE(
    t.JSON, '$[*]'
    COLUMNS (
      age NUMBER PATH '$.age',
      opinion VARCHAR2(4000) PATH '$.opinion',
      id number PATH '$.id',
      name VARCHAR2(4000) PATH '$.name'
    )
) jt WHERE jt.opinion <> 'somevalue');

如果我这样修改它:

UPDATE table t SET t.JSON = (SELECT JSON_ARRAYAGG(
      JSON_OBJECT(
        'id' VALUE jt.id,
        'opinion' VALUE jt.opinion,
        'age' VALUE jt.age,
        'name' VALUE jt.name
      ) RETURNING CLOB )
FROM JSON_TABLE(
    t.JSON, '$[*]'
    COLUMNS (
      age NUMBER PATH '$.age',
      opinion VARCHAR2(4000) PATH '$.opinion',
      id number PATH '$.id',
      name VARCHAR2(4000) PATH '$.name'
    )
) jt WHERE jt.opinion <> 'somevalue') WHERE t.id = 10;

我在唯一修改的行上收到了错误的预期值(就像单个修改行中所有行的所有JSON一样)。我想知道发生了什么,方法是否正确。
PS:请考虑JSON不是col的真实的名称,所以它不会与任何东西冲突。

enxuqcxy

enxuqcxy1#

如果你在19号。10或更高,使用json_transform更容易。
搜索表达式'$[*]?(@.opinion == "somevalue")'标识opinion为“somevalue”的数组元素。使用remove子句将这些条目从文档中删除:

with rws ( id, j ) as (
  select 10, '[{"id":4, "name":"Jhon", age:40, opinion:null},{"id":3, name:"Jane", age:7},{"id":7, "name":"Peter", age:12, opinion:"somevalue"}]' from dual union all
  select 20, '[{"id":10, "name":"Julian", age:40, opinion:"somevalue"}]'  from dual union all
  select 30, '[{"id":30, "name":"Paul", age:20, opinion:"opinion"},{"id":3, name:"Jane", age:7}]'  from dual 
)
  select json_transform (
    j,
    remove '$[*]?(@.opinion == "somevalue")'
  )
  from   rws;
  
JSON_TRANSFORM(J,REMOVE'$[*]?(@.OPINION=="SOMEVALUE")')                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
-------------------------------------------------------------------------------------
[{"id":4,"name":"Jhon","age":40,"opinion":null},{"id":3,"name":"Jane","age":7}]
[]
[{"id":30,"name":"Paul","age":20,"opinion":"opinion"},{"id":3,"name":"Jane","age":7}]

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