Sql Server Temporal table history

Question

Is there a way to identify deleted rows in history from the table?

So when I perform an updated or a delete it moves data to the history, I want to know which rows in history were deleted

help

Answer 1

You can use the output clause. For example:

declare @ids table (id int);

delete from t
    output deleted.id into @ids
    where . . .;

select *
from @ids;

Answer 2

Use a semi-anti join between the temporal table and the history table based on the PK.

Answer 3

As an example...

CREATE SCHEMA _CHRONO;
GO

CREATE TABLE dbo.TEMPO
(
ID          INT IDENTITY PRIMARY KEY,
SOME_DATA   VARCHAR(32),
_DH_DEB     DATETIME2 GENERATED ALWAYS AS ROW START HIDDEN NOT NULL,
_DH_FIN     DATETIME2 GENERATED ALWAYS AS ROW END   HIDDEN NOT NULL,
PERIOD FOR SYSTEM_TIME (_DH_DEB, _DH_FIN)
)
WITH (SYSTEM_VERSIONING = ON (HISTORY_TABLE = _CHRONO.TEMPO));
GO

INSERT INTO dbo.TEMPO VALUES ('a data'), ('another data')
GO

DELETE FROM dbo.TEMPO WHERE SOME_DATA LIKE '%other%'
GO

And now the query retrieving deleted rows:

SELECT CT.*
FROM   _CHRONO.TEMPO AS CT
       LEFT OUTER JOIN dbo.TEMPO AS T
          ON CT.ID = T.ID

retrieving the last version of the deleted rows needs to add some extra SQL conditions

Answer 4

If you want to know which rows were deleted in history, just create an audit table and have a trigger in the real table.

For example, you have a table called "PeopleTbl".

1- You will create an audit table to store the history of "PeopleTbl". Let's create a table called "PeopleAuditTbl".

The structure of the "PeopleAuditTbl". Should have all the columns that you wish to keep track of and a time field and a TypeField(Delete, Inserted, or Updated).

2- Now in your "PeopleTbl". You will create a trigger that stores updated or delete (You can also store inserted records if you want.

The trigger for delete should be something like this.

ALTER TRIGGER T_PeopleTbl
    ON PeopleTbl
    AFTER DELETE
AS
INSERT INTO PeopleAuditTbl(
        //Fields you want to store
        Date,
        TypeField
    )
    SELECT
        //Fields you want to store
        GETDate(),
        'DELETE'
    FROM DELETED

Answer 5

If you are looking to use your Temporal History table to identify the records that have been deleted from the Main table, the following example demonstrates how this can be achieved:

-- Create a Temporal Table for demonstration purposes
CREATE TABLE dbo.Invoice
(
  InvoiceId int identity(1,1) PRIMARY KEY CLUSTERED
  , InvoiceDate date NOT NULL
  -- Other fields...
  , SysStartTime datetime2 GENERATED ALWAYS AS ROW START
  , SysEndTime datetime2 GENERATED ALWAYS AS ROW END
  , PERIOD FOR SYSTEM_TIME (SysStartTime, SysEndTime)
 )
WITH (SYSTEM_VERSIONING = ON (HISTORY_TABLE = dbo.InvoiceHistory));
go

-- Create some dummy data
insert into Invoice(InvoiceDate) values ('2020-01-01'),('2020-02-01')
go
WAITFOR DELAY '00:00:03'
go
delete from Invoice where InvoiceId=1
go

-- Get Current Records
select * from Invoice

-- Get Deleted Records
;with cte as
(
    select InvoiceId, MAX(SysEndTime) [SysEndTime]
    from Invoice FOR SYSTEM_TIME ALL
    group by InvoiceId
    having MAX(SysEndTime) < '9999-12-31'
)
select i.*
from Invoice FOR SYSTEM_TIME ALL i
inner join cte c on (i.InvoiceId=c.InvoiceId and i.SysEndTime=c.SysEndTime)

Basically, we're looking at the union of the main and history tables ( select * from Invoice FOR SYSTEM_TIME ALL ) for any records where the latest version is no longer valid ( MAX(SysEndTime) < '9999-12-31' )