1. Ch 5. Introducing More Database Objects

2. Database Objects Table (ch2) View (ch3) Stored Procedure Trigger Function User-defined types

3. Stored Procedures A collection of code stored as an object in the database Accepts parameters Allows all T-SQL statements Can be called with EXECUTE statement

4. Types of Stored Procedures System Stored Procedures T-SQL Stored Procedures CLR Procedures Extended stored procedures

5. System Stored Procedure Pre-defined stored procedures to perform maintenance and management activities

6. System Stored Procedures

7. System Stored Procedure sp_help, xp_logininfo, sp_monitor, sp_who etc…

8. T-SQL Stored Procedures Benefit: Code Reusability reduce network traffic – centrally stored on the server Permission-based execution – only user with valid permission can execute it Security – Prevent SQL Injection attacks

9. T-SQL Stored Procedure Create a table using following code CREATE TABLE Employees( EmployeeID int IDENTITY(1,1) Primary key NOT NULL, Employeename nvarchar(200) NULL, EmployeeSSN int NULL, msg nchar(10) NULL ) EmployeeIDEmployeeNameEmployeeSSNmsg

10. T-SQL Stored Procedure TO create a stored procedure to insert CREATE PROCEDURE InsertEmployee ( @Name nvarchar(200), @SSN int ) AS INSERT INTO Employees (EmployeeName, EmployeeSSN) VALUES (@Name, @SSN)

11. T-SQL Stored Procedure To test our stored procedure: InsertEmployee ‘Tester’, 123456789 Go InsertEmployee ‘Tester2’, 987654321 Go InsertEmployee ‘Tester3’, 111111111 Go

12. T-SQL Stored Procedure TO create a stored procedure to Update a row CREATE PROCEDURE UpdateEmployee ( @ID int, @Name nvarchar(200), @SSN int ) AS UPDATE Employees SET EmployeeName=@Name, EmployeeSSN=@SSN WHERE EmployeeID = @ID

13. T-SQL Stored Procedure To test our stored procedure: UpdateEmployee 0, ‘Update Tester’,123456789

14. T-SQL Stored Procedure TO create a stored procedure to Delete a row CREATE PROCEDURE DeleteEmployee ( @ID int ) AS DELETE FROM Employees WHERE EmployeeID = @ID

15. T-SQL Stored Procedure To test our stored procedure: DeleteEmployee 0

16. CLR Stored Procedure Access to objects/methods outside of MS SQL Server 2005 Uses.Net CLR (Common Language runtime) For complex calculations or methods that require access to objects outside of SQL Server Exercise 5.1

17. Triggers Group of code that will automatically execute when a certain event occur DML trigger (Data Manipulation Language) - Insert, Update, Delete table opereations DDL Trigger (Data Defination Language) – database/Server events

18. DML Insert Trigger CREATE TRIGGER trg_Insert ON [dbo].[Employees] FOR INSERT AS DECLARE @ID int SELECT @ID = EmployeeID FROM INSERTED UPDATE Employees SET msg = 'Inserted' WHERE EmployeeID = @ID

19. DML Update Trigger CREATE TRIGGER trg_Update ON [dbo].[Employees] FOR UPDATE AS DECLARE @ID int SELECT @ID = EmployeeID FROM DELETED IF UPDATE(EmployeeName) UPDATE Employees SET msg = 'Updated' WHERE EmployeeID = @ID

20. DML Delete Trigger CREATE TRIGGER trg_Delete ON [dbo].[Employees] FOR DELETE AS DECLARE @ID int SELECT @ID = EmployeeID FROM DELETED ROLLBACK BEGIN TRANSACTION --remove transaction error UPDATE Employees SET msg = 'Deleted' WHERE EmployeeID = @ID

21. DML Instead of Trigger Completely ‘skip’ the insert/update/delete event, then execute the trigger Still populates INSERTED, DELETED internal table

22. DML Instead of Trigger CREATE TRIGGER trg_InsteadUpdate ON [dbo].[Employees] INSTEAD OF UPDATE AS BEGIN IF UPDATE(EmployeeName) DECLARE @ID int SELECT @ID = EmployeeID FROM DELETED UPDATE Employees SET msg = 'I_Update' WHERE EmployeeID = @ID END

23. DML Instead of Trigger CREATE TRIGGER trg_InsteadDelete ON [dbo].[Employees] INSTEAD OF DELETE AS BEGIN DECLARE @ID int SELECT @ID = EmployeeID FROM DELETED UPDATE Employees SET msg = 'I_Deleted' WHERE EmployeeID = @ID END

24. DDL Trigger A group of code to automatically fire on any DDL event (create table, drop table …) New in SQL 2005 Page 156-157

25. DDL Trigger CREATE TRIGGER trg_block_ddl ON DATABASE FOR DDL_DATABASE_LEVEL_EVENTS AS RAISERROR('database locked for ddl events',16,1) ROLLBACK TRANSACTION

26. Trigger Nesting A trigger event that was fired by another trigger SQL Server supports up to 32 levels, after which the trigger will be canceled Disable Trigger Nesting SP_CONFIGURE ‘nested_triggers’,0 RECONFIGURE

27. Trigger Recursion Direct Recursion – Trigger perform a statement that will cause itself to be fired InDirect Recursion – Trigger1 perform a statement that will fire Trigge2 which will fire Trigger1, repeat

28. Trigger Recursion CREATE TRIGGER [trg_RecursiveInsert] ON [dbo].[Employees] FOR INSERT AS DECLARE @Name nvarchar(200) DECLARE @SSN int SELECT @Name = EmployeeName, @SSN = EmployeeSSN FROM Employees EXECUTE InsertEmployee @Name, @SSN

29. Disable Trigger Recursion Disable (Direct) Recursive Trigger ALTER DATABASE databasename SET RECURSIVE_TRIGGER OFF Disable (inDirect) Recursive Trigger SP_CONFIGURE ‘nested_triggers’,0 RECONFIGURE

30. Functions Similar to a stored procedure except it can be called within a SELECT statement Type of Function: Scalar Function Table-valued function Built-in function CLR function

31. Functions Create this table CREATE TABLE [dbo].[EmployeeInfo] ( [EmployeeInfoID] [int] IDENTITY(1,1) PRIMARY KEY NOT NULL, [EmployeeID] [int] NOT NULL, [DOB] [datetime] NULL, )

32. Scalar Functions CREATE FUNCTION [dbo].[Age] ( @DOB datetime ) RETURNS int AS BEGIN DECLARE @Age int SELECT @Age = Datediff(yyyy,@DOB,GetDate()) RETURN @Age END GO

33. Scalar Functions To test our function: SELECT *, dbo.Age(EmployeeInfo.DOB) FROM Employee INNER JOIN EmployeeInfo ON Employee.EmployeeID = EmployeeInfo.EmployeeID

34. Table-valued Functions CREATE FUNCTION [dbo].[getTable] () RETURNS TABLE AS ( SELECT Employee.EmployeeName, dbo.Age(EmployeeInfo.DOB) AS AGE FROM Employee INNER JOIN EmployeeInfo ON Employee.EmployeeID = EmployeeInfo.EmployeeID )

35. Table-valued Functions Can be used to return a whole table To test our table-valued function select * from getTable()

36. Built-in Functions Much like built-in stored procedures

37. Function - Determinism Deterministic function - always return the same value Non-Deterministic Function – may return different value each time

38. Function - Determinism A Non-Deterministic function CREATE FUNCTION getTime ( @ExtraDay int ) RETURNS datetime AS BEGIN RETURN DateAdd(day,@ExtraDay, GetDate()) END GO

39. Function - Determinism A Deterministic function CREATE FUNCTION getSquare @InputNumber int ) RETURNS int AS BEGIN RETURN (@inputNumber*@InputNumber) END GO

40. User-Defined Types Create an alias to an existing data type Only have ability to set length and NOT NULL option Created using SP_addtype

41. User-Defined Types Open a new database query in SYBEX EXEC sp_addtype ssn, ‘VARCHAR(11)’, ‘NOT NULL’ Create a table with user defined type CREATE TABLE Employees (EmployeeID int identity (1,1), Employeename nvarchar(200), DepartmentID int, EmployeeSSN ssn)