Triggers

USE AdventureWorks2012;
GO
IF OBJECT_ID ('Purchasing.LowCredit','TR') IS NOT NULL
   DROP TRIGGER Purchasing.LowCredit;
GO
-- This trigger prevents a row from being inserted in the Purchasing.PurchaseOrderHeader table
-- when the credit rating of the specified vendor is set to 5 (below average).  
  
CREATE TRIGGER Purchasing.LowCredit ON Purchasing.PurchaseOrderHeader  
AFTER INSERT  
AS  
IF (ROWCOUNT_BIG() = 0)
RETURN;
IF EXISTS (SELECT 1  
           FROM inserted AS i   
           JOIN Purchasing.Vendor AS v   
           ON v.BusinessEntityID = i.VendorID  
           WHERE v.CreditRating = 5  
          )  
BEGIN  
RAISERROR ('A vendor''s credit rating is too low to accept new  
purchase orders.', 16, 1);  
ROLLBACK TRANSACTION;  
RETURN   
END;  
GO  
  
-- This statement attempts to insert a row into the PurchaseOrderHeader table  
-- for a vendor that has a below average credit rating.  
-- The AFTER INSERT trigger is fired and the INSERT transaction is rolled back.  
  
INSERT INTO Purchasing.PurchaseOrderHeader (RevisionNumber, Status, EmployeeID,  
VendorID, ShipMethodID, OrderDate, ShipDate, SubTotal, TaxAmt, Freight)  
VALUES (  
2  
,3  
,261  
,1652  
,4  
,GETDATE()  
,GETDATE()  
,44594.55  
,3567.564  
,1114.8638 );  
GO