SQL Server triggers - insert new rows into audit table - sql

Question

I have a simple table as below.
I want to create a trigger to insert new values into "SectionsAudit" Table.
Means:
If a new row is inserted into the Sections table, I want to insert the same row into the Audit table
If an existing row is updated in the Sections table, I want to create a new row in the Audit table with the updated row.
How can I do that in SQL Server? Also, I would like to know if this a good practice?
CREATE TABLE [dbo].[Sections]
(
[Id] int IDENTITY(1,1) NOT NULL,
[Name] varchar(25) NOT NULL,
[InsertedBy] varchar(25) NOT NULL,
[InsertedDateTime] datetime NOT NULL,
[UpdatedBy] varchar(25) NOT NULL,
[UpdatedDateTime] datetime NOT NULL,
CONSTRAINT [PK_Id] PRIMARY KEY CLUSTERED([Id])
)

Answer 1

The trigger will look something like this, its a good practice depending of the MS SQL version you're using.
Note that for using this approach is necessary to have in your dbo.SectionsAudit a field to track the ModificationId of the original Record (in the example I called it IdModi)
CREATE TRIGGER [dbo].[tr_SectionsAudit]
ON [dbo].[Sections]
AFTER INSERT, UPDATE
NOT FOR REPLICATION
AS
BEGIN
-- SET NOCOUNT ON added to prevent extra result sets from
-- interfering with SELECT statements.
SET NOCOUNT ON;
INSERT SectionsAudit
(Id, IdModi, fieldname, ...)
SELECT Id, IdModi = (ISNULL((SELECT ISNULL(MAX(SA.IdModi), 0)
FROM SectionsAudit SA
WHERE SA.Id = I.Id
) , 0) + 1),
fieldname, ...
FROM INSERTED I
END

Answer 2

In your case I suggest you to use Rowversion or Change Data Capture.
Below some option to do it:
Rowversion
It is a unique binary numbers of 8 bytes. It is updated every time that you insert or update any column of any records
Example:
CREATE TABLE dbo.Test (ID int PRIMARY KEY, RowVersion rowversion) ;
Change Data Capture
Change data capture records insert, update, and delete activity that is applied to a SQL Server table. This makes the details of the changes available in an easily consumed relational format. Column information and the metadata that is required to apply the changes to a target environment is captured for the modified rows and stored in change tables that mirror the column structure of the tracked source tables. Table-valued functions are provided to allow systematic access to the change data by consumers.
Temporal Tables
Start from SQLServer 2016 you can use the system-versioned temporal table that is a type of user table designed to keep a full history of data changes and allow easy point in time analysis. This type of temporal table is referred to as a system-versioned temporal table because the period of validity for each row is managed by the system (i.e. database engine).
Every temporal table has two explicitly defined columns, each with a datetime2 data type. These columns are referred to as period columns. These period columns are used exclusively by the system to record period of validity for each row whenever a row is modified.
Example:
CREATE TABLE dbo.test
(
[ID] int NOT NULL PRIMARY KEY CLUSTERED
,[ValidFrom] datetime2 GENERATED ALWAYS AS ROW START
,[ValidTo] datetime2 GENERATED ALWAYS AS ROW END
,PERIOD FOR SYSTEM_TIME (ValidFrom, ValidTo))
WITH (SYSTEM_VERSIONING = ON (HISTORY_TABLE = dbo.TestHistory));
Triggers
Creates a DML, DDL, or logon trigger. A trigger is a special type of stored procedure that automatically runs when an event occurs in the database server. DML triggers run when a user tries to modify data through a data manipulation language (DML) event. DML events are INSERT, UPDATE, or DELETE statements on a table or view. These triggers fire when any valid event fires, whether table rows are affected or not.