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使用 PostgreSQL 12.7，我想从嵌套的 JSON 数组中获取产品的最新版本（最大值）。以下是“AAA”列fields中的示例值：product

 "customfield_01":[
      {
         "id":1303,
         "name":"AAA - 1.82.0",
         "state":"closed",
         "boardId":137,
         "endDate":"2021-10-15T10:00:00.000Z",
         "startDate":"2021-10-04T01:00:01.495Z",
         "completeDate":"2021-10-18T03:02:55.824Z"
      },
      {
         "id":1304,
         "name":"AAA - 1.83.0",
         "state":"active",
         "boardId":137,
         "endDate":"2021-10-29T10:00:00.000Z",
         "startDate":"2021-10-18T01:00:24.324Z"
      }
   ],

我试过了：

SELECT product, jsonb_path_query_array(fields, '$.customfield_01.version') AS version
FROM product.issues;

这是输出：

| product | version                                       |
|---------------------------------------------------------|
| CCC     |[]                                             |
| AAA     |["AAA - 1.83.0", "AAA - 1.82.0"]               |
| BBB     |["BBB - 1.83.0", "BBB - 1.82.0", "BBB - 1.84.0]|
| BBB     |["BBB - 1.83.0"]                               |
| BBB     |["BBB - 1.84.0", "BBB - 1.83.0"]               |

预期是：

| product | version                                       |
|---------------------------------------------------------|
| AAA     |["AAA - 1.83.0"                                |
| BBB     |["BBB - 1.84.0]                                |
| BBB     |["BBB - 1.83.0"]                               |
| BBB     |["BBB - 1.84.0"]                               |

尝试了 unnest/Array 但它抛出了一个错误：

SELECT max(version)
FROM  (SELECT UNNEST(ARRAY [jsonb_path_query_array(fields,'$.customfield_01.version')]) AS version FROM product.issues ) AS version;

确实使用了-1，但它只会获得最右边的数据。

jsonb_path_query_array(fields, '$.customfield_01.version') ->> -1

Postgres 和 json 非常新。确实尝试阅读文档和谷歌，但多次尝试失败。

4

1 回答 1

1

假设product是您的表的主键列。

您可以使用SQL/JSON 路径表达式：

SELECT product, max(version) AS latest_version
FROM   product.issues;
     , jsonb_array_elements_text(jsonb_path_query_array(fields, '$.customfield_01.name')) AS version 
GROUP  BY 1
ORDER  BY 1;

但是简单jsonb的操作符也能达到同样的效果：

SELECT product, max(version ->> 'name') AS latest_version
FROM   product.issues
     , jsonb_array_elements(fields -> 'customfield_01') AS version
GROUP  BY 1
ORDER  BY 1;

使用jsonb_array_elements()orjsonb_array_elements_text()取消嵌套jsonb数组。看：

unnest()（就像您尝试过的那样）可用于取消嵌套Postgres 数组。

当然，max()只有在“最新版本”按字母顺序排在最后时才有效。否则，提取版本部分并将所有部分处理为数字。喜欢：

SELECT i.product, v.*
FROM   issues i
LEFT   JOIN LATERAL (
   SELECT version ->> 'name' AS version, string_to_array(split_part(version ->> 'name', ' - ', 2), '.')::int[] AS numeric_order
   FROM   jsonb_array_elements(i.fields -> 'customfield_01') AS version
   ORDER  BY 2 DESC NULLS LAST
   LIMIT  1
   ) v ON true;

db<>在这里摆弄

看：

于 2021-10-24T17:51:13.207 回答