CREATE TRIGGER FOR INSERT, UPDATE, DELETE : Trigger for Delete « Trigger « SQL Server / T-SQL Tutorial

1. SQL Server / T-SQL Tutorial
2. Trigger
3. Trigger for Delete

2> CREATE TABLE Orders (
3>      OrderID int IDENTITY (1, 1) NOT NULL ,
4>      CustomerID nchar (5) NULL ,
5>      EmployeeID int NULL ,
6>      OrderDate datetime NULL ,
7>      RequiredDate datetime NULL ,
8>      ShippedDate datetime NULL ,
9>      ShipVia int NULL ,
10>     Freight money NULL DEFAULT (0),
11>     ShipName nvarchar (40) NULL ,
12>     ShipAddress nvarchar (60) NULL ,
13>     ShipCity nvarchar (15) NULL ,
14>     ShipRegion nvarchar (15) NULL ,
15>     ShipPostalCode nvarchar (10) NULL ,
16>     ShipCountry nvarchar (15) NULL
17> )
18> GO
1>    CREATE TRIGGER Order2DependsOnOrders
2>       ON Orders
3>       FOR INSERT, UPDATE, DELETE
4>    AS
5>       DECLARE @Count int
6>       SELECT @Count = COUNT(*) FROM DELETED
7>       IF @Count > 0
8>       BEGIN
9>          IF NOT EXISTS
10>             (
11>              SELECT 'True'
12>              FROM Deleted d
13>              LEFT JOIN Orders o
14>                 ON d.OrderID = o.OrderID
15>              WHERE o.OrderID IS NULL
16>             )
17>          BEGIN
18>             RAISERROR('Record Exists In Orders Table. Delete Cancelled.',16,1)
19>             ROLLBACK TRAN
20>          END
21>       END
22>       IF @@ERROR != 0
23>          ROLLBACK TRAN
24>       SELECT @Count = COUNT(*) FROM INSERTED
25>       SELECT 'Count is ' + CONVERT(varchar,@Count) + ' Before Delete'
26>       IF @Count > 0
27>       BEGIN
28>          IF EXISTS
29>             (
30>              SELECT 'True'
31>              FROM Inserted i
32>              LEFT JOIN Orders o
33>                 ON i.OrderID = o.OrderID
34>              WHERE o.OrderID IS NULL
35>             )
36>          BEGIN
37>             RAISERROR('Inserted Record Must exist in the Orders Table',16,1)
38>             ROLLBACK TRAN
39>          END
40>       END
41>       IF @@ERROR != 0
42>          ROLLBACK TRAN
43>       GO
1>       drop TRIGGER Order2DependsOnOrders;
2>       GO
1>       drop table Orders;
2>       GO