從審計記錄構建快照表

Question

我有一個Customer表，其結構如下。

CustomerId Name Address Phone 
1   Joe 123 Main NULL 

我也有一個Audit表跟蹤更改Customer表。

Id Entity EntityId Field OldValue  NewValue  Type AuditDate 
1 Customer 1   Name  NULL   Joe   Add 2016-01-01 
2 Customer 1   Phone NULL   567-54-3332 Add 2016-01-01 
3 Customer 1   Address NULL   456 Centre Add 2016-01-01 
4 Customer 1   Address 456 Centre 123 Main  Edit 2016-01-02 
5 Customer 1   Phone 567-54-3332 843-43-1230 Edit 2016-01-03 
6 Customer 1   Phone 843-43-1230 NULL   Delete 2016-01-04 

我將每日ETL作業被填充的CustomerHistory報告表。它與客戶表具有相同的字段，其他字段爲SnapShotDate。

我需要編寫一個查詢，其中包含Audit表中的記錄，如下所示，轉換並插入CustomerHistory。

CustomerId Name Address  Phone   SnapShotDate 
1   Joe 456 Centre 567-54-3332 2016-01-01 
1   Joe 123 Main  567-54-3332 2016-01-02 
1   Joe 123 Main  843-43-1230 2016-01-03 
1   Joe 123 Main  NULL   2016-01-04 

我想解決方案將涉及審計表或遞歸CTE的自聯接。我希望在開發此解決方案方面有任何幫助。

注意：不幸的是，我沒有選擇使用觸發器或更改審計表模式。查詢性能不是問題，因爲這將是夜間ETL過程。

Answer 1

您可以使用下面的腳本。

DROP TABLE #tmp 

CREATE TABLE #tmp (
    id INT Identity 
    , EntityId INT 
    , NAME VARCHAR(10) 
    , Address VARCHAR(100) 
    , Phone VARCHAR(20) 
    , Type VARCHAR(10) 
    , SnapShotDate DATETIME 
    ) 

;with cte1 as (
select AuditDate, EntityId, Type, [Name], [Address], [Phone] 
from 
    (select AuditDate, EntityId, Type, Field, NewValue from #Audit) p 
pivot 
    (
    max(NewValue) 
    for Field in ([Name], [Address], [Phone]) 
    ) as xx 
) 
insert into #tmp (EntityId, Name, Address, Phone, Type, SnapShotDate) 
select EntityId, Name, Address, Phone, Type, AuditDate 
from cte1 


-- update NULLs columns with the most recent value 
update #tmp 
set Name = (select top 1 Name from #tmp tp2 
      where EntityId = tp2.EntityId and Name is not null 
      order by id desc) 
where Name is null 

update #tmp 
set Address = (select top 1 Address from #tmp tp2 
       where EntityId = tp2.EntityId and Address is not null 
       order by id desc) 
where Address is null 

update #tmp 
set Phone = (select top 1 Phone from #tmp tp2 
      where EntityId = tp2.EntityId and Phone is not null 
      order by id desc) 
where Phone is null 

創建Test Data，

CREATE TABLE #Customer (
    CustomerId INT 
    , NAME VARCHAR(10) 
    , Address VARCHAR(100) 
    , Phone VARCHAR(20) 
    ) 

INSERT INTO #Customer 
VALUES (1, 'Joe', '123 Main', NULL) 

CREATE TABLE #Audit (
    Id INT 
    , Entity VARCHAR(50) 
    , EntityId INT 
    , Field VARCHAR(20) 
    , OldValue VARCHAR(100) 
    , NewValue VARCHAR(100) 
    , Type VARCHAR(10) 
    , AuditDate DATETIME 
    ) 

insert into #Audit values 
(1, 'Customer', 1,   'Name'  ,NULL   ,'Joe'   ,'Add' ,'2016-01-01'), 
(2, 'Customer', 1,   'Phone' ,NULL   ,'567-54-3332' ,'Add' ,'2016-01-01'), 
(3, 'Customer', 1,   'Address' ,NULL   ,'456 Centre' ,'Add' ,'2016-01-01'), 
(4, 'Customer', 1,   'Address' ,'456 Centre' ,'123 Main'  ,'Edit' ,'2016-01-02'), 
(5, 'Customer', 1,   'Phone' ,'567-54-3332' ,'843-43-1230' ,'Edit' ,'2016-01-03'), 
(6, 'Customer', 1,   'Phone' ,'843-43-1230' ,NULL   ,'Delete' ,'2016-01-04'), 
(7, 'Customer', 2,   'Name'  ,NULL   ,'Peter'  ,'Add' ,'2016-01-01'), 
(8, 'Customer', 2,   'Phone' ,NULL   ,'111-222-3333' ,'Add' ,'2016-01-01'), 
(8, 'Customer', 2,   'Address' ,NULL   ,'Parthenia' ,'Add' ,'2016-01-01') 

結果

EntityId Name Address  Phone   Type SnapShotDate 
1   Joe  456 Centre 567-54-3332  Add  2016-01-01 
1   Joe  123 Main 843-43-1230  Edit 2016-01-02 
1   Joe  123 Main 843-43-1230  Edit 2016-01-03 
1   Joe  123 Main 843-43-1230  Delete 2016-01-04