临时表：特定列仅更改版本详细信息

Question

在查询时态表方面需要帮助/想法。我在表上启用了 SQL 版本控制。该表目前有 15 列。

确切的要求是确定“OrderStatus”列更新了多少次以及谁在什么时间更新了它？我们只想查看在默认情况下选择所有其他列的特定日期之间“OrderStatus”列更新了多少次。

Answer 1

您的问题缺少一些细节，所以我根据一些假设进行了尝试。

[re-]创建代表表

IF Object_ID('dbo.orders', 'U') IS NOT NULL
  BEGIN
    ALTER TABLE dbo.orders SET (SYSTEM_VERSIONING = OFF);
  END
;
DROP TABLE IF EXISTS dbo.orders_history;
DROP TABLE IF EXISTS dbo.orders;

CREATE TABLE dbo.orders (
   OrderId     int         NOT NULL IDENTITY(9,37)
 , OrderStatus varchar(20) NOT NULL
 , UpdatedBy   varchar(20) NOT NULL
 , ValidFrom   datetime2 GENERATED ALWAYS AS ROW START
 , ValidTo     datetime2 GENERATED ALWAYS AS ROW END
 , PERIOD FOR SYSTEM_TIME (ValidFrom, ValidTo)
 , CONSTRAINT pk_dbo_orders PRIMARY KEY (OrderId)
)
WITH (
  SYSTEM_VERSIONING = ON (
    HISTORY_TABLE = dbo.orders_history
  )
);

创建示例数据

请注意，使用WAITFOR 是为了在事件之间提供一些更具说明性的间隙。

INSERT INTO dbo.orders (OrderStatus, UpdatedBy)
  VALUES ('NEW', 'George')
       , ('NEW', 'George')
;
WAITFOR DELAY '00:00:02';

UPDATE dbo.orders
SET    OrderStatus = 'IN PROGRESS'
WHERE  OrderId = 9
;
WAITFOR DELAY '00:00:02';

-- Mark both orders as despatched
UPDATE dbo.orders
SET    OrderStatus = 'DESPATCHED'
;
WAITFOR DELAY '00:00:02';

-- Whoops, order #46 wasn't supposed to be marked as dispatched
UPDATE dbo.orders
SET    OrderStatus = 'IN PROGRESS'
WHERE  OrderId = 46
;
WAITFOR DELAY '00:00:02';

-- Mark it as in progress again, but changing the person who did the operation
UPDATE dbo.orders
SET    OrderStatus = 'IN PROGRESS'
     , UpdatedBy   = 'Not George'
WHERE  OrderId = 46
;
WAITFOR DELAY '00:00:02';

-- _Now_ it is despatched
UPDATE dbo.orders
SET    OrderStatus = 'DESPATCHED'
     , UpdatedBy   = 'George'
WHERE  OrderId = 46
;

原始数据

让我们来看看原始数据

SELECT OrderId
     , OrderStatus
     , UpdatedBy
     , ValidFrom
     , ValidTo
FROM   dbo.orders FOR SYSTEM_TIME ALL
ORDER
    BY OrderId
     , ValidFrom
;

OrderId	OrderStatus	UpdatedBy	ValidFrom	ValidTo
9	NEW	George	2021-02-17 10:27:35.1632525	2021-02-17 10:27:37.1719903
9	IN PROGRESS	George	2021-02-17 10:27:37.1719903	2021-02-17 10:27:39.1852032
9	DESPATCHED	George	2021-02-17 10:27:39.1852032	9999-12-31 23:59:59.9999999
46	NEW	George	2021-02-17 10:27:35.1632525	2021-02-17 10:27:39.1852032
46	DESPATCHED	George	2021-02-17 10:27:39.1852032	2021-02-17 10:27:41.1995704
46	IN PROGRESS	George	2021-02-17 10:27:41.1995704	2021-02-17 10:27:43.2171042
46	IN PROGRESS	Not George	2021-02-17 10:27:43.2171042	2021-02-17 10:27:45.2328908
46	DESPATCHED	Still Not George	2021-02-17 10:27:45.2328908	9999-12-31 23:59:59.9999999

查询时间

; WITH _orders AS (
  SELECT OrderId
       , OrderStatus
       , UpdatedBy
       , ValidFrom
       , ValidTo
       , Lead(OrderStatus) OVER (PARTITION BY OrderId ORDER BY ValidFrom) AS NextOrderStatus
  FROM   dbo.orders FOR SYSTEM_TIME ALL
)
SELECT OrderId
     , OrderStatus
     , UpdatedBy
     , ValidFrom
FROM   _orders
WHERE  OrderStatus <> NextOrderStatus -- Only return records where the order status has changed
OR     NextOrderStatus IS NULL -- Include the "most recent" record in the results, always.
ORDER
    BY OrderId
     , ValidFrom
;

结果

OrderId	OrderStatus	UpdatedBy	ValidFrom
9	NEW	George	2021-02-17 10:27:35.1632525
9	IN PROGRESS	George	2021-02-17 10:27:37.1719903
9	DESPATCHED	George	2021-02-17 10:27:39.1852032
46	NEW	George	2021-02-17 10:27:35.1632525
46	DESPATCHED	George	2021-02-17 10:27:39.1852032
46	IN PROGRESS	Not George	2021-02-17 10:27:43.2171042
46	DESPATCHED	Still Not George	2021-02-17 10:27:45.2328908

Answer 2

版本控制无法为您提供此信息，因为在“更新相同值”的情况下，将创建一个版本化行，但您将永远无法查看该列是否已被修改或其他。

唯一的方法是在表中创建一个触发器并在某个对象中计数。

在这种情况下，我使用分析器的 10 个用户可配置计数器之一... 例如，触发器的代码：

CREATE TRIGGER E_U_MY_TABLE
ON dbo.MY_TABLE
FOR UPDATE
AS
SET NOCOUNT 1;
IF NOT UPDATE(OrderStatus)
   RETURN;
DECLARE @COUNT BIGINT = (SELECT cntr_value 
                         FROM   sys.dm_os_performance_counters 
                         WHERE instance_name = 'User counter 1') + 1;
EXEC sp_user_counter1 @COUNT;
GO

您可以随时阅读：

SELECT cntr_value 
FROM   sys.dm_os_performance_counters 
WHERE instance_name = 'User counter 1'

Answer 3

您尝试做的问题是历史记录表没有说明哪些列已更新。

那么我们需要做的是首先查询这些日期之间的所有rowversions，然后使用LAG/LEAD检查该行是否发生了变化。

问题：如果我们要求给定日期，我们不会得到之前的版本。为此，我们需要再次查询该表。在主查询中使用BETWEEN（包括）而不是FROM（不包括）会使这变得更加困难，因为我们必须找到一种方法来获取行< @start

SELECT *
FROM (
    SELECT *,
        ROW_NUMBER() OVER (PARTITION BY pkID ORDER BY SysStartTime) rn,   -- or whatever your startTime column is called
        LAG(OrderStatus) OVER (PARTITION BY pkID ORDER BY SysStartTime) PrevStatus
    FROM myTable t
    FOR SYSTEM_TIME FROM @start TO @end    -- FROM is strictly exclusive
) t

WHERE PrevStatus <> OrderStatus OR
    (rn = 1 AND EXISTS (SELECT 1
        FROM myTable t2
        FOR SYSTEM_TIME AT @start
        WHERE t2.ID = t.ID
            AND t2.OrderStatus <> t.OrderStatus
    ))

---

变更数据捕获

使用 CDC，设置查询有点复杂，但我想它会执行得更好。

您通常会使用fn_cdc_get_column_ordinal 来获取列号，然后在WHERE 中使用它来过滤更新掩码。

您还需要将最近收到的@lsn 传递为binary(10)（如果从新开始，则为空binary(10)）。您会在下面的第一个结果集中收到新的。

DECLARE @from_lsn binary(10) = sys.fn_cdc_get_min_lsn('myTable');  -- get the new low mark
DECLARE @to_lsn binary(10) = sys.fn_cdc_get_max_lsn();  --get the new high mark
SELECT @to_lsn;    -- send back the new high, which becomes the low on the next run

SET @lsn = sys.fn_cdc_increment_lsn (@lsn);   -- get next LSN after the old high
IF (sys.fn_cdc_get_min_lsn (N'myTable') > @lsn)
    SELECT * FROM myTable;       -- need to do a full refresh
ELSE
BEGIN
    DECLARE @ordinal int = sys.fn_cdc_get_column_ordinal (N'myTable', N'myCol');
    SELECT *
    FROM sys.fn_cdc_get_all_changes_capture_myTable
        (@from_lsn, @to_lsn, 'all')
    WHERE sys.fn_cdc_is_bit_set (__$update_mask, @ordinal) = 1;
END;