POSTGRESQL 从 jsonb 中提取密钥

Posted 2023-04-12

【中文标题】POSTGRESQL 从 jsonb 中提取密钥

【英文标题】：POSTGRESQL extract keys from jsonb

【发布时间】：2021-07-07 13:22:32

【问题描述】：

我有一个包含大量外部数据的 jsonb 列的表，我需要提取一些键，但我很难做到。

桌子是这样的：

代码标题 external_data G20540 数据分析

外部数据是 jsonb 列，在数组中用 dict 组织，它有以下信息：

[
    
        "DESCR": "Requisito RJ_GRD_GCSOSRJ",
        "ORDERNO": "10",
        "ACAD_PLAN": "",
        "ACAD_PROG": "",
        "DESCR254A": "Requisito RJ_GRD_GCSOSRJ_Plan. de Comunicação I",
        "DESCRSHORT": "Requisito",
        "EFF_STATUS": "A",
        "RQ_CONNECT": "",
        "ACAD_CAREER": "",
        "INSTITUTION": "X",
        "PARENTHESIS": "",
        "SAA_DESCR80": "Requisito RJ_GRD_GCSOSRJ_Plan. de Comunicação I",
        "RQRMNT_GROUP": "000312",
        "ACAD_SUB_PLAN": "",
        "CREATION_DATE": "2020-04-13T21:26:51.923",
        "RQRMNT_USEAGE": "ENR",
        "CONDITION_CODE": "CRS",
        "CONDITION_DATA": "003130",
        "REQUISITE_TYPE": "PRE",
        "CONDITION_DESCR": "ID Curso",
        "RQRMNT_LIST_SEQ": "1",
        "RQ_GRP_LINE_NBR": "0010",
        "RQ_LINE_KEY_NBR": "0001",
        "RQ_GRP_LINE_TYPE": "CRSE",
        "CONDITION_OPERATOR": "EQ"
    
]

我需要提取“DESCR”、“ORDENO”、“DESCR254A”、“SAA_DESCR80”、“RQRMNT_GROUP”、“RQRMNT_USEAGE”、“EFF_STATUS”。

我尝试了这个查询，但我只得到了 external_data 列的空结果：

SELECT codes.external_id as "code"
    ,codes.title as "title"
    ,requirements.external_data ->> 'RQRMNT_GROUP' as "RQRMNT_GROUP"
    ,requirements.external_data ->> 'EFF_STATUS' as "EFF_STATUS"
    ,requirements.external_data ->> 'RQRMNT_USEAGE' as "RQRMNT_USEAGE"
    ,requirements.external_data ->> 'DESCR' as "DESCR"
    ,requirements.external_data ->> 'SAA_DESCR80' as "SAA_DESCR80"
    ,requirements.external_data ->> 'DESCR254A' as "DESCR254A"
    ,requirements.external_data ->> 'ORDERNO' as "ORDERNO"
FROM requirements
LEFT JOIN codes ON codes.id = requirements.code_id

我该怎么做？

【问题讨论】：

您的 JSON 值是一个数组。您需要使用-> 0 ->> 'RQRMNT_GROUP' 来访问第一个数组元素。如果数组包含多个元素，你想要什么结果

谢谢！成功了！

【参考方案1】：

您需要使用WITH 子句来识别数组中的表并从中进行选择：

WITH external_codes AS (
   SELECT r.code_id,
          jsonb_array_elements(r.external_data) AS external_data
   FROM requirements r
)
SELECT codes.external_id as "code"
    ,codes.title as "title"
    ,external_codes.external_data ->> 'RQRMNT_GROUP' as "RQRMNT_GROUP"
    ,external_codes.external_data ->> 'EFF_STATUS' as "EFF_STATUS"
    ,external_codes.external_data ->> 'RQRMNT_USEAGE' as "RQRMNT_USEAGE"
    ,external_codes.external_data ->> 'DESCR' as "DESCR"
    ,external_codes.external_data ->> 'SAA_DESCR80' as "SAA_DESCR80"
    ,external_codes.external_data ->> 'DESCR254A' as "DESCR254A"
    ,external_codes.external_data ->> 'ORDERNO' as "ORDERNO"
FROM external_codes
LEFT JOIN codes ON codes.id = external_codes.code_id