PostGreSql - 提取jsonb數據

本文主要介紹如何在PostGreSql中提取出jsonb類型字段中的某個key的值

參考：https://www.cnblogs.com/mywebnumber/p/5551092.html

一、簡單模式

1. 只有一個{}

   # rule_config 字段格式
   {
     "cardType": 1,
     "sellPrice": null,
     "originPrice": 15
   }
   
   # 獲取cardType SELECT
       rule_config -> 'cardType' AS cardType 
   FROM
       t_free_ride_card_rule_config 
   WHERE
       title = '測試0211'

   　　
2. 只有一個[]

   # rule_config字段格式
   [
     "zero",
     "one",
     "two"
   ]
   
   # 獲取第一個元素
   SELECT
       rule_config ->0  AS cardType 
   FROM
       t_free_ride_card_rule_config 
   WHERE
       title = '測試0211'

    

3. 兩個{}並列

   # rule_config字段格式
   [
     {
       "ruleGuid": "1125720873758932994",
       "mcardType": 1,
       "packStart": "2020-02-14",
       
     },
     {
       "ruleGuid": "1073055433702576129",
       "mcardType": 1,
       "packExpire": "2020-02-18"
     }
   ]
   
   # 獲取key為ruleGuid 和 ruleGuid 的值
   SELECT
       json_array_elements ( rule_config :: json ) -> 'ruleGuid' AS ruleGuid,
       json_array_elements ( rule_config :: json ) -> 'mcardType' AS mcardType 
   FROM
       t_free_ride_card_rule_config 
   WHERE
       title = '測試0211'

    

二、復雜格式

• jsonb數據格式如下

  [
    {
      "platform": 0,
      "cardPackage": [
        {
          "ruleGuid": "1125720873758932994",
          "mcardType": 1,
          "packStart": "2020-02-14",
          "packExpire": "2020-02-15"
        },
        {
          "ruleGuid": "1073055433702576129",
          "mcardType": 1,
          "packStart": "2020-02-16",
          "packExpire": "2020-02-18"
        }
      ],
      "platformExpire": "2020-02-18"
    }
  ]

   

• 獲取相關字段的sql

  # 第一種，嵌套sql
  SELECT
      bottom :: json ->> 'ruleGuid' AS ruleGuid 
  FROM
      (
      SELECT
          json_array_elements ( cardPackage ) AS bottom 
      FROM
          ( SELECT expire_info :: json -> 'cardPackage' AS cardPackage FROM ( SELECT expire_info :: json -> 0 AS expire_info FROM t_ev_month_card WHERE user_new_id = '1200107139' ) AS A ) AS B 
      ) AS F
  
  說明：
  第一層sql：SELECT expire_info :: json -> 0 AS expire_info FROM t_ev_month_card WHERE user_new_id = '1200107139' 獲取到最外層1個{}的數據，命名為expire_info列
  第二層sql：從最外層花括號里expire_info獲取到 key = “cardPackage” 的內容 expire_info :: json -> 'cardPackage' ，命名為 cardPackage列
  第三層sql：將cardPackage列的內容分為單獨的{}
  第四層sql：從每個單獨的{}中取出ruleGuid字段（見 一、（1）節）

  
  # 第二種，
  SELECT (json_array_elements((expire_info -> 0):: json ->'cardPackage'))->'ruleGuid' AS a
  FROM t_ev_month_card WHERE user_new_id = '1200107139'
  

   如果數據類型是jsonb，也可以將json替換成jsonb:

　　

SELECT
    bottom :: jsonb -> 'ruleGuid' AS ruleGuid 
FROM
    (
    SELECT
        jsonb_array_elements ( cardPackage ) AS bottom 
    FROM
        (
        SELECT
            expire_info :: jsonb -> 'cardPackage' AS cardPackage 
        FROM
            (
            SELECT
                expire_info :: jsonb -> 0 AS expire_info 
            FROM
                t_ev_month_card 
            WHERE
                user_new_id = '1200107139' 
            ) AS A 
        ) AS B 
    ) AS F