azure - Azure Synapse Analytics 上此代码中的 WITH (jsonContent varchar(MAX)) AS [result] 的含义是什么

Question

我无法理解为什么我们要写with (doc nvarchar(max)) as rows

JSON FILE

{"date_rep":"2020-07-24","day":24,"month":7,"year":2020,"cases":3,"deaths":0,"geo_id":"AF"}
{"date_rep":"2020-07-25","day":25,"month":7,"year":2020,"cases":7,"deaths":0,"geo_id":"AF"}
{"date_rep":"2020-07-26","day":26,"month":7,"year":2020,"cases":4,"deaths":0,"geo_id":"AF"}
{"date_rep":"2020-07-27","day":27,"month":7,"year":2020,"cases":8,"deaths":0,"geo_id":"AF"}

打开此 JSON 文件的代码从这里开始。

select
    JSON_VALUE(doc, '$.date_rep') AS date_reported,
    JSON_VALUE(doc, '$.countries_and_territories') AS country,
    CAST(JSON_VALUE(doc, '$.deaths') AS INT) as fatal,
    JSON_VALUE(doc, '$.cases') as cases,
    doc
from openrowset(
        bulk 'https://demoaccname.dfs.core.windows.net/demoadlscontainer/afg.json',

        format = 'csv',
        fieldterminator ='0x0b',
        fieldquote = '0x0b'
    ) with (doc nvarchar(max)) as rows

Answer 1

jsonContent nvarchar(max) 创建一个列名为 jsonContent 的外部表。

in 
FROM
    OPENROWSET(
        BULK 'https://XXXXX',
        FORMAT = 'CSV',
        FIELDQUOTE = '0x0b',
        FIELDTERMINATOR ='0x0b',
        ROWTERMINATOR = '0x0b'
    )  with (**jsonContent nvarchar(max)**) as rows