How to make a Trigger on Master-Detail - sql-server

Question

I Have the following scenario:
CREATE TABLE dbo.Orders
(
OrderID int IDENTITY (1,1) NOT NULL
, OrderVersion int DEFAULT(1)
, Customer varchar(30)
, ScheduleDate date
, PaymentOption int
);
CREATE TABLE dbo.OrdersItems
(
OrderItemsID int IDENTITY (1,1) NOT NULL
, OrderID int
, Product varchar(100)
, Qty int
, value decimal(18,2)
);
CREATE TABLE dbo.logOrders
(
OrderID int NOT NULL
, OrderVersion int DEFAULT(1)
, Customer varchar(30)
, ScheduleDate date
, PaymentOption int
);
CREATE TABLE dbo.logOrdersItems
(
OrderItemsID int NOT NULL
, OrderID int
, Product varchar(100)
, Qty int
, value decimal(18,2)
);
-- Insert values into the table.
INSERT INTO dbo.Orders (Customer , ScheduleDate, PaymentOption)
VALUES ('John', 2016-09-01, 1);
INSERT INTO dbo.OrdersItems( OrderId, Product, Qty, Value)
VALUES (1, 'Foo', 20, 35.658),
(1, 'Bla', 50, 100)
(1, 'XYZ', 10, 3589)
First Statement
UPDATE Orders set ScheduleDate = 2016-10-05 WHERE OrderId = 1
Second Statement
Delete From OrdersItems WHERE OrderItemsID = 2
UPDATE OrdersItems set Qty = 5 WHERE OrderItemsID = 1
Third Statement
Update Orders set PaymentOption = 2 WHERE OrderId = 1
Update OrdersItems set Value = 1050 WHERE OrderItemsID = 3
I am trying to figure out how to make a trigger that after each one of the Statements Sample above Insert on the log Tables the data before the changing. And setting the OrderVersion to OrderVersion + 1 on table Orders.
So on the log Tables I will have all versions after the later one.
Is it possible to make a single trigger to monitor both tables and execute getting the original data before the UPDATE, DELETE , INSERT statement to get the original data and INSERT on the logTables ?
Here comes a sample to explain better what result I want.
This is the Initial Data on table Orders and OrdersItems
If I make an Update on Orders ( any column ) or Make an Update,Insert,Delete on OrdersItems I need to Insert on respectively logTables the data on the image.
And with this I'll have on logOrders and logItems the original data and on the Orders and Items the altered data.
I Hope I could explain better what I mean.

Answer 1

You will need two triggers. The trigger for the Orders table handles Orders table update/delete. The trigger for the OrdersItems table does the same for OrdersItems. The triggers look like this:
For the Orders table:
CREATE TRIGGER dbo.Orders_trigger
ON dbo.Orders
AFTER DELETE,UPDATE
AS
BEGIN
SET NOCOUNT ON;
INSERT INTO dbo.logOrders
SELECT * FROM DELETED;
INSERT INTO dbo.logOrdersItems
SELECT oi.* FROM OrdersItems oi
WHERE oi.OrderID IN (SELECT OrderId FROM DELETED);
END
GO
For OrdersItems:
CREATE TRIGGER dbo.OrdersItems_trigger
ON dbo.OrdersItems
AFTER DELETE,UPDATE
AS
BEGIN
SET NOCOUNT ON;
--Inerst the changed/deleted OrdersItems into the log
INSERT INTO dbo.logOrdersItems
SELECT * FROM DELETED
--Inserts the unchanged sibling OrdersItems records into the log
INSERT INTO dbo.logOrdersItems
SELECT oi.* FROM OrdersItems oi
WHERE oi.OrderId IN (SELECT DISTINCT OrderId FROM DELETED)
AND oi.OrderItemsID NOT IN (SELECT DISTINCT OrderItemsID FROM DELETED);
INSERT INTO dbo.logOrders
SELECT o.* FROM Orders o
WHERE o.OrderID IN (SELECT DISTINCT OrderId FROM DELETED);
END
GO
The Orders Trigger is fairly straightforward. Use the virtual DELETED table to insert the original version of the records into the log. Then join to the child OrdersItems records and insert them into the log as well. The way this is written, it will work even if you update or delete multiple Order records at a time.
The OrdersItems Trigger is a bit more complicated. You need to log the pre-chage version of the OrdersItems and Orders Records. But you also want (I think) to log the unchanged "sibling" OrdersItems records as well so that you have a complete picture of the records.
I know this is just your sample data, but you will want to add some kind of a timestamp to the records in the log tables. Otherwise you just end up with a bunch of duplicate rows and you cannot tell which is which. At the beginning of the trigger you can create a variable to hold the update datetime and then append that to your INSERT statement for the logs.
DECLARE #UpdateDateTime DATETIME;
SET #UpdateDateTime = GETUTCDATE();