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我正在努力处理一些 SQL，它应该将两个表中的数据连接在一起，但我还需要将 JSON 数组解析为输出表中的行......

以下是我想加入的 2 个表的示例：

命令

订单号 交货日期
1 2020-05-18 07:00:00.000
2 2020-08-31 07:30:00.000

和历史：

订单号 历史_详情
1 [{"FieldName":"OrderStatusType.Description","FieldType":"String","ValueBefore":"Delivered","ValueAfter":"Undelivered","Action":2}]
1 [{"FieldName":"VoucherCode","FieldType":"String","ValueBefore":"","ValueAfter":"64646456","Action":1},{"FieldName":"PricingType.Description" ,"FieldType":"String","ValueBefore":"Standard","ValueAfter":"Discount","Action":2}]
2 [{"FieldName":"InitialComment","FieldType":"String","ValueBefore":"","ValueAfter":"Test Comment","Action":2},{"FieldName":"Appointment.Date ","FieldType":"DateTime","ValueBefore":"2020-08-06T07:30:00.000","ValueAfter":"2020-08-31T07:30:00.000","Action":0}]
2 无效的

（不幸的是，字符串“null”，而不是 NULL - 我们在加入数据时必须处理）

我想要得到的是这样的输出：

订单号 交货日期 字段名 之前的价值 价值之后
1 2020-05-18 07:00:00.000 OrderStatusType.Description 发表 未送达
1 2020-05-18 07:00:00.000 优惠券代码 64646456
1 2020-05-18 07:00:00.000 定价类型.描述 标准 折扣
2 2020-08-31 07:30:00.000 初始评论 测试评论
2 2020-08-31 07:30:00.000 约会日期 2020-08-06T07:30:00.000 2020-08-31T07:30:00.000

我可以自己做这两个查询，我只是在努力加入他们......

即，这给了我一切，而没有分解 JSON：

SELECT
  o.order_number as [Order Number],
  o.delivery_date as [Delivery Date],
  oh.history_details as [History]
FROM [dbo].[Order] o
JOIN [dbo].[History] oh on oh.order_number = o.order_number
WHERE oh.history_details != 'null'

虽然我可以像这样进行 JSON 映射：

DECLARE @json NVARCHAR(MAX)
SET @json='[{"FieldName":"VoucherCode","FieldType":"String","ValueBefore":"","ValueAfter":"64646456","Action":1},{"FieldName":"PricingType.Description","FieldType":"String","ValueBefore":"Standard","ValueAfter":"Discount","Action":2}]';
SELECT *
FROM OPENJSON(@json)
WITH (   
   FieldName   varchar(200) '$.FieldName' ,  
   ValueBefore     varchar(200)     '$.ValueBefore',  
   ValueAfter varchar(200) '$.ValueAfter'  
 )

我真的很难弄清楚如何将这两者结合在一起并获得我正在寻找的结果，很多 OPENJSON 示例就像我上面的示例一样，它们似乎期望单个列/数据类型。

4

2 回答 2

1

您可以使用OUTER APPLY将数据从History表中推送到OPENJSON.

我们可以NULLIF用来清除任何表示字符串的 JSON'null'

SELECT
  o.order_number as [Order Number],
  o.delivery_date as [Delivery Date],
  j.FieldName,
  j.ValueBefore,
  j.ValueAfter
FROM [dbo].[Order] o
JOIN [dbo].[History] oh on oh.order_number = o.order_number
OUTER APPLY OPENJSON(NULLIF(oh.history_details, 'null'))
WITH (   
   FieldName   varchar(200) '$.FieldName' ,  
   ValueBefore     varchar(200)     '$.ValueBefore',  
   ValueAfter varchar(200) '$.ValueAfter'  
 ) j

正如其他人所提到的，同一列中不能有不同的数据类型，所以它必须保持varchar.

于 2021-03-26T13:44:05.573 回答
1

您的问题在这里有一点问题，因为您想要的输出与您问题的其余部分相矛盾。同一列中不能有不同的数据类型，因此在为每个值保留适当的数据类型的同时，无法获得所需的输出。

您的选择是将数据保留为文本字符串，因为它显示在 JSON 中，或者为可以捕获的每种可能的数据类型设置多个列。

如果这只是一个用于捕获更改历史记录的日志表，而您不会定期查询，那么您可能只需将值保留为文本字符串即可。

询问

declare @Order table(Order_Number int,Delivery_Date datetime);
insert into @Order values
 (1,'2020-05-18 07:00:00.000')
,(2,'2020-08-31 07:30:00.000')
;

declare @History table(Order_Number int, History_Details varchar(max));
insert into @History values
 (1,'[{"FieldName":"OrderStatusType.Description","FieldType":"String","ValueBefore":"Delivered","ValueAfter":"Undelivered","Action":2}]')
,(1,'[{"FieldName":"VoucherCode","FieldType":"String","ValueBefore":"","ValueAfter":"64646456","Action":1},{"FieldName":"PricingType.Description","FieldType":"String","ValueBefore":"Standard","ValueAfter":"Discount","Action":2}]')
,(2,'[{"FieldName":"InitialComment","FieldType":"String","ValueBefore":"","ValueAfter":"Test Comment","Action":2},{"FieldName":"Appointment.Date","FieldType":"DateTime","ValueBefore":"2020-08-06T07:30:00.000","ValueAfter":"2020-08-31T07:30:00.000","Action":0}]')
,(2,'null')
;

select o.Order_Number
      ,o.Delivery_Date
      ,j.FieldName
      ,j.ValueBefore
      ,j.ValueAfter

      ,case when j.FieldType = 'String' then j.ValueBefore end as ValueBeforeString
      ,case when j.FieldType = 'DateTime' then try_convert(datetime,j.ValueBefore,127) end as ValueBeforeDateTime
      ,case when j.FieldType = 'String' then j.ValueAfter end as ValueAfterString
      ,case when j.FieldType = 'DateTime' then try_convert(datetime,j.ValueAfter,127) end as ValueAfterDateTime
from @Order as o
    join @History as h
        on o.Order_Number = h.Order_Number
    outer apply openjson(h.History_Details)
                with (FieldName   varchar(200) '$.FieldName' 
                     ,FieldType   varchar(200) '$.FieldType'
                     ,ValueBefore varchar(200) '$.ValueBefore'
                     ,ValueAfter  varchar(200) '$.ValueAfter'
                     ) as j
where h.History_Details <> 'null'
order by o.Order_Number
        ,o.Delivery_Date;

输出

订单号 交货日期 字段名 之前的价值 价值之后 ValueBeforeString ValueBeforeDateTime 值后字符串 值后日期时间
1 2020-05-18 07:00:00.000 OrderStatusType.Description 发表 未送达 发表 无效的 未送达 无效的
1 2020-05-18 07:00:00.000 优惠券代码 64646456 无效的 64646456 无效的
1 2020-05-18 07:00:00.000 定价类型.描述 标准 折扣 标准 无效的 折扣 无效的
2 2020-08-31 07:30:00.000 初始评论 测试评论 无效的 测试评论 无效的
2 2020-08-31 07:30:00.000 约会日期 2020-08-06T07:30:00.000 2020-08-31T07:30:00.000 无效的 2020-08-06 07:30:00.000 无效的 2020-08-31 07:30:00.000
于 2021-03-26T12:13:35.670 回答