1. Views
Views
CREATE VIEW AS
Uses for Views

2. Views
Views are definitions of queries that can be treated like tables
Only the view definition is stored
When the view is called the definition is applied against current data in the database and that data is fed into the query that calls the view
Views have several advantages
Serve as a security measure
Simplify complicated queries
Perform tasks difficult to perform in a query
Encapsulate frequently used query segments for reuse

3. Use a CREATE VIEW Statement to create a view
CREATE VIEW vw_SuppliersWithProducts AS
SELECT Suppliers.SupplierID, CompanyName, Country,
ProductID, ProductName
FROM Suppliers INNER JOIN Products
ON Suppliers.SupplierID = Products.SupplierID
SELECT * FROM vw_SuppliersWithProducts

4. Using Views for Special Operations
Remember this UNION query?
How can we get the results sorted by CompanyName?
SELECT CAST(SupplierID AS char(10)) AS 'ID',
CompanyName, 'Supplier' AS 'Type'
FROM Suppliers
UNION
SELECT CAST(CustomerID AS char(10)) AS 'ID',
CompanyName, 'Customer' AS 'Type'
FROM Customers

5. Using Views for Special Operations (cont.)
Define the query as a View
Query the view with ORDER BY
CREATE VIEW vw_Companies AS
SELECT CAST(SupplierID AS char(10)) AS 'ID',
CompanyName, 'Supplier' AS 'Type'
FROM Suppliers
UNION
SELECT CAST(CustomerID AS char(10)) AS 'ID',
CompanyName, 'Customer' AS 'Type'
FROM Customers
SELECT *
FROM vw_Companies
ORDER BY CompanyName

6. CREATE VIEW creates the view as a permanent object in the DB
Managing Views
CREATE VIEW creates the view as a permanent object in the DB
You can delete it from the Views tree node or use DROP VIEW viewname
You cannot create two views with the same name
ALTER VIEW viewname followed by a view definition will replace the old view with the new definition