sql—从json数组中提取每个值作为唯一行

niwlg2el 于 2021-07-26 发布在 Java

关注(0)|答案(3)|浏览(418)

这是我的问题

%jdbc(presto)
select
    cast(json_extract(basicmetadata, '$.locales') as array<map<varchar, json>>)
from 
    escherbird.entities
where
    entityid = 1262415487625019394
    and domainid = 124

它返回这个数组

[{country="IN", hashCode=1828207720, _passthroughFields={}, language="en"}, {country="AU", hashCode=1899888409, _passthroughFields={}, language="en"}, {country="GB", hashCode=-2002878675, _passthroughFields={}, language="en"}, {country="IE", hashCode=-358794848, _passthroughFields={}, language="en"}, {country="CA", hashCode=392726027, _passthroughFields={}, language="en"}, {country="NZ", hashCode=-136386876, _passthroughFields={}, language="en"}, {country="US", hashCode=-1355251774, _passthroughFields={}, language="en"}]

这个查询给我一个空结果

%jdbc(presto)
select
    cast(json_extract(basicmetadata, '$.locales.country') as array<map<varchar, json>>)
from 
    escherbird.entities
where
    entityid = 1262415487625019394
    and domainid = 124

如何编写查询以将每个国家作为唯一行返回？

sql presto JSON Arrays

来源：https://stackoverflow.com/questions/61967084/extract-each-value-from-json-array-as-unique-row

3条答案

按热度按时间

ruarlubt1#

以下是在sql server 2016及更高版本中运行的查询，

DECLARE @JSONDATA NVARCHAR(MAX);
    SET 
      @JSONDATA = N'{"domainId":29,"locales":[{"language":"en","country":"IN"},{"language":"en","country":"AU"}]}';
    SELECT 
      COUNTRY 
    FROM 
      OPENJSON(@JSONDATA) WITH (
        LOCALES NVARCHAR(MAX) '$.locales' AS JSON
      ) CROSS APPLY OPENJSON(LOCALES, '$') WITH (
        COUNTRY NVARCHAR(2) '$.country'
      );

以下是在oracle server中运行的查询

SELECT 
  * 
FROM 
  JSON_TABLE(
    '{"domainId":29,"locales":[{"language":"en","country":"IN"},{"language":"en","country":"AU"}]}', 
    '$.locales[*]' COLUMNS (
      -- L_ROWNUM FOR ORDINALITY,
      L_COUNTRY VARCHAR2(10) PATH '$.country'
    )
  )

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pjngdqdw2#

如果您使用的是postgres，您可以使用：

select c.item ->> 'country' as country
from the_table t
  cross join jsonb_array_elements(t.json_column -> 'locales') as c(item);

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jxct1oxe3#

这是一个对象类型，如果您想在表中显示它，应该将其转换为数组。
即。：

var Array_name = Object.keys(object_name);

然后你可以用这个作为数组

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sql—从json数组中提取每个值作为唯一行

3条答案

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