如何修复有时缺少偏移量的SQL表order-by DateTimeOffset

Question

我有一个乱七八糟的表，里面充满了事件，有时会得到一个DateTime，而在其他地方，会有一个DateTimeOffset被分配给Date字段，类似于这样(假设你住的地方离分割王国的经度足够远)：

DECLARE @MY_LOG TABLE ([MOMENT] DATETIMEOFFSET, [PAYLOAD] NVARCHAR(200));

INSERT INTO @MY_LOG ([MOMENT],[PAYLOAD]) VALUES (GETDATE(),'first entry')
WAITFOR DELAY '00:00:00.100';
INSERT INTO @MY_LOG ([MOMENT],[PAYLOAD]) VALUES (SYSDATETIMEOFFSET(),'second entry')
WAITFOR DELAY '00:00:00.100';
INSERT INTO @MY_LOG ([MOMENT],[PAYLOAD]) VALUES (GETDATE(),'third entry')
WAITFOR DELAY '00:00:00.100';
INSERT INTO @MY_LOG ([MOMENT],[PAYLOAD]) VALUES (SYSDATETIMEOFFSET(),'forth entry')

SELECT [MOMENT],[PAYLOAD] FROM @MY_LOG ORDER BY [MOMENT] ASC;

最后一次select的结果如下所示：

2020-03-31 02:39:10.6779279 +02:00  second entry
2020-03-31 02:39:10.8809259 +02:00  forth entry
2020-03-31 02:39:10.5730000 +00:00  first entry
2020-03-31 02:39:10.7770000 +00:00  third entry

我试图通过使用SWITCHOFFSET来修复它，它添加了丢失的偏移量，但也补偿了它：

SELECT [MOMENT],
       [PAYLOAD],
       CASE WHEN DATEPART(tz,[MOMENT])=0 THEN SWITCHOFFSET(MOMENT, '+02:00') ELSE MOMENT END AS FIXED 
FROM @MY_LOG ORDER BY FIXED ASC;

结果是：

2020-03-31 02:39:10.6779279 +02:00  second entry 2020-03-31 02:39:10.6779279 +02:00
2020-03-31 02:39:10.8809259 +02:00  forth entry  2020-03-31 02:39:10.8809259 +02:00
2020-03-31 02:39:10.5730000 +00:00  first entry  2020-03-31 04:39:10.5730000 +02:00
2020-03-31 02:39:10.7770000 +00:00  third entry  2020-03-31 04:39:10.7770000 +02:00

我可能还需要考虑像This question中那样的切换时刻，但现在我正在寻找一种非破坏性(只读)的解决方案来按日期对行进行排序

Answer 1

在发布之前找到了答案:通过转换为datetime2(7)来剥离偏移量

SELECT [MOMENT],
       [PAYLOAD],
       CONVERT(datetime2(7),[MOMENT]) AS FIXED
FROM @MY_LOG ORDER BY FIXED ASC;

结果是一个正确排序的表(除了每年两个小时的夏令时转换)。

2020-03-31 03:04:04.3630000 +00:00  first entry  2020-03-31 03:04:04.3630000
2020-03-31 03:04:04.4689375 +02:00  second entry 2020-03-31 03:04:04.4689375
2020-03-31 03:04:04.5670000 +00:00  third entry  2020-03-31 03:04:04.5670000
2020-03-31 03:04:04.6709404 +02:00  forth entry  2020-03-31 03:04:04.6709404