1. Module 7: Implementing Views

2. Overview Introduction to Views Creating and Managing Views
Optimizing Performance by Using Views

3. Lesson 1: Introduction to Views
What Is a View?
Types of Views
Advantages of Views

4. What Is a View? Employee (table) vEmployee (view) EmployeeID LastName
FirstName
Title …
287
Mensa-Annan
Tete
Mr.
288
Abbas
Syed
289
Valdez
Rachel
NULL
vEmployee (view)
LastName
FirstName
Mensa-Annan
Tete
Abbas
Syed
Valdez
Rachel

5. Types of Views Standard views
Combine data from one or more base tables (or views) into a new virtual table
Indexed views
Materialize (persist) the view through the creation of a unique clustered index on the view
Partitioned views
Join horizontally partitioned data from one or more base tables across one or more servers

6. Advantages of Views Focus the data for a user Mask database complexity
Simplify management of user permissions
Improve performance
Organize data for export to other applications

7. Lesson 2: Creating and Managing Views
Syntax for Creating Views
Demonstration: Creating a View
Syntax for Altering and Dropping Views
How Ownership Chains Affect Views
Sources of Information About Views
View Encryption
Considerations for Modifying Data in a View
Practice: Creating a View

8. Syntax for Creating Views
Use CREATE VIEW Transact-SQL statement:
Restrictions:
Cannot nest more than 32 levels deep
Cannot contain more than 1,024 columns
Cannot use COMPUTE, COMPUTE BY, or INTO
Cannot use ORDER BY without TOP
CREATE VIEW [ schema_name.] view_name [ (column [ ,...n ] ) ] [WITH [ENCRYPTION] [SCHEMABINDING] [VIEW_METADATA] ] AS select_statement [ ; ] [ WITH CHECK OPTION ]

9. Demonstration: Creating a View
In this demonstration, you will see how to:
Create a view
Query a view
Generate a script for a view

10. Syntax for Altering and Dropping Views
Alter by using the ALTER VIEW Transact-SQL statement:
Drop by using the DROP VIEW Transact-SQL statement:
ALTER VIEW [ schema_name.]view_name [ (column [ ,...n ] ) ] [WITH [ENCRYPTION] [SCHEMABINDING] [VIEW_METADATA] ] AS select_statement [ ; ] [ WITH CHECK OPTION ]
DROP VIEW [ schema_name.]view_name [ ...,n ] [ ; ]

11. How Ownership Chains Affect Views2
View Owner: Mary
Access view 1
User: John
Dependency 3
View Owner: Mary
Dependency 4
Table Owner: Tim

12. Sources of Information About Views
SQL Server Management Studio
Transact-SQL
Source
Information
Object Explorer
List of views in database
Access to columns, triggers, indexes, and statistics defined on views
View Properties dialog box
Properties of individual views
Source
Information
sys.views
List of views in database
sp_helptext
Definition of non-encrypted views
sys.sql_dependencies
Objects (including views) that depend on other objects

13. View Encryption
Use the WITH ENCRYPTION option on CREATE VIEW Transact-SQL statement
Encrypts view definition in sys.syscomments table
Protects view creation logic
CREATE VIEW [HumanResources].[vEmployee] WITH ENCRYPTION AS SELECT e.[EmployeeID],c.[Title],c.[FirstName],c.[MiddleName] ,c.[LastName],c.[Suffix],e.[Title] AS [JobTitle] ,c.[Phone],c.[ Address] FROM [HumanResources].[Employee] e INNER JOIN [Person].[Contact] c ON c.[ContactID] = e.[ContactID]
Use WITH ENCRYPTION on ALTER VIEW statements to retain encryption

14. Considerations for Modifying Data in a View
Views do not maintain a separate copy of data (indexed views are an exception)
Updates to views modify base tables
Restrictions:
Cannot affect more than one base table
Cannot modify columns derived from aggregate functions or calculations
Cannot modify columns affected by GROUP BY, HAVING, or DISTINCT clauses
Updates to views are restricted by using the WITH CHECK OPTION

15. Practice: Creating a View
In this practice, you will create a view

16. Lesson 3: Optimizing Performance by Using Views
Performance Considerations for Views
What Is an Indexed View?
What Is a Partitioned View?

17. Performance Considerations for Views
Views introduce performance overhead because views are resolved dynamically
Nested views introduce risk of performance problems
Review definition of unencrypted nested views
Use SQL Server Profiler to review performance
Indexed views and partitioned views can improve performance

18. What Is an Indexed View? A view with a unique clustered index
Materializes view, improving performance
Allows query optimizer to use view in query resolution
Use when:
Performance gains outweigh maintenance overhead
Underlying data is modified infrequently
Queries perform a significant number of joins and aggregations
CREATE UNIQUE CLUSTERED INDEX [IX_vStateProvinceCountryRegion] ON [Person].[vStateProvinceCountryRegion] ( [StateProvinceID] ASC, [CountryRegionCode] ASC)

19. What Is a Partitioned View?
Joins horizontally partitioned data from a set of tables across one or more servers
SQLServerNorth.Sales.Sale
SQLServerSouth.Sales.Sale
CREATE VIEW vSales AS SELECT * FROM SQLServerNorth.Sales.Sale
UNION ALL SELECT * FROM SQLServerSouth.Sales.Sale
vSales

20. Lab: Implementing Views
Exercise 1: Creating Views
Exercise 2: Creating Indexed Views
Exercise 3: Creating Partitioned Views