1. SQL Views Appendix C DATABASE CONCEPTS, 3rd Edition
DAVID M. KROENKE and DAVID J. AUER
DATABASE CONCEPTS, 3rd Edition
Appendix C
SQL Views

2. Appendix Objectives Learn basic SQL statements for creating views
Learn basic SQL statements for using views
Understand the reasons for using views
KROENKE and AUER - DATABASE CONCEPTS (3rd Edition)
© 2008 Pearson Prentice Hall

3. SQL Views
A SQL view is a virtual table that is constructed from other tables or views
A view has no data of its own, but uses data stored in tables or other views
Views are created using SQL SELECT statements
Views are used in other SELECT statements just as if they were a table
The SQL statements that create the views may not contain an ORDER BY clause
If the results of a query using a view need to be sorted, the sort order must be provided by the SELECT statement that processes the view
KROENKE and AUER - DATABASE CONCEPTS (3rd Edition)
© 2008 Pearson Prentice Hall

4. SQL CREATE VIEW Statement
The SQL CREATE VIEW statement is used to create view structures.
CREATE VIEW ViewName AS
{SQL SELECT statement};
KROENKE and AUER - DATABASE CONCEPTS (3rd Edition)
© 2008 Pearson Prentice Hall

5. SQL CREATE VIEW Example
CREATE VIEW EmployeePhoneView AS
SELECT FirstName, LastName,
Phone AS EmployeePhone
FROM EMPLOYEE;
KROENKE and AUER - DATABASE CONCEPTS (3rd Edition)
© 2008 Pearson Prentice Hall

6. Creating a SQL View in SQL Server 2005
Click the New Query button, enter the SQL for the view just as you would enter the SQL for a query, and then click the Execute button to create the query
The “Command(s) completed successfully” message in the Messages window indicates that the view has been created
The new view appears in the expanded Views folder after it is created
KROENKE and AUER - DATABASE CONCEPTS (3rd Edition)
© 2008 Pearson Prentice Hall

7. Creating a SQL View MySQL 5.x
Enter the SQL for the view just as you would enter the SQL for a query, and then click the Execute button to create the query
The new view appears in the expanded wpc schema after it is created (you may have to refresh the schema for it to appear)
The “Query returned no resultset” message indicates that the view has been created
KROENKE and AUER - DATABASE CONCEPTS (3rd Edition)
© 2008 Pearson Prentice Hall

8. Using an SQL CREATE
Once the view is created, it can be used in the FROM clause of SELECT statements just like a table.
SELECT *
FROM EmployeePhoneView
ORDER BY LastName;
KROENKE and AUER - DATABASE CONCEPTS (3rd Edition)
© 2008 Pearson Prentice Hall

9. Using the EmployeePhoneView in SQL Server 2005
Click the New Query button, enter the SQL for the query that uses the view, and then click the Execute button to create the query
The query results appear in the Results window.
KROENKE and AUER - DATABASE CONCEPTS (3rd Edition)
© 2008 Pearson Prentice Hall

10. Using the EmployeePhoneView in MySQL 5.X
Enter the SQL for the query that uses the view, and then click the Execute button to create the query
The query results appear in the Resultset window.
Use the File | New Resultset Tab command to open a new Resultset window
KROENKE and AUER - DATABASE CONCEPTS (3rd Edition)
© 2008 Pearson Prentice Hall

11. Some Uses for SQL Views Hide columns or rows
Display results of computations
Hide complicated SQL syntax
Layer built-in functions
KROENKE and AUER - DATABASE CONCEPTS (3rd Edition)
© 2008 Pearson Prentice Hall

12. Using SQL Views: Hide columns or rows I
CREATE VIEW BasicDepartmentDataView AS
SELECT DepartmentName,
Phone AS DepartmentPhone
FROM DEPARTMENT;
SELECT * FROM BasicDepartmentDataView
ORDER BY DepartmentName;
KROENKE and AUER - DATABASE CONCEPTS (3rd Edition)
© 2008 Pearson Prentice Hall

13. Using SQL Views: Hide columns or rows II
CREATE VIEW MarkingDepartmentProjectView AS
SELECT ProjectID, Name AS ProjectName,
MaxHours, StartDate, EndDate
FROM PROJECT
WHERE Department = 'Marketing';
SELECT * FROM MarkingDepartmentProjectView
ORDER BY ProjectID;
KROENKE and AUER - DATABASE CONCEPTS (3rd Edition)
© 2008 Pearson Prentice Hall

14. Using SQL Views: Display results of computations – SQL Statement
CREATE VIEW ProjectHoursToDateView AS
SELECT PROJECT.ProjectID,
Name AS ProjectName,
MaxHours AS ProjectMaxHours,
SUM(HoursWorked) AS ProjectHoursWorkedToDate
FROM PROJECT, ASSIGNMENT
WHERE PROJECT.ProjectID =
ASSIGNMENT.ProjectID
GROUP BY PROJECT.ProjectID;
KROENKE and AUER - DATABASE CONCEPTS (3rd Edition)
© 2008 Pearson Prentice Hall

15. Using SQL Views: Display results of computations - Results
SELECT * FROM ProjectHoursToDateView
ORDER BY PROJECT.ProjectID;
KROENKE and AUER - DATABASE CONCEPTS (3rd Edition)
© 2008 Pearson Prentice Hall

16. Using SQL Views: Hide complicated SQL syntax – SQL Statement
CREATE VIEW EmployeeProjectHoursWorkedView AS
SELECT Name, FirstName, LastName,
HoursWorked
FROM EMPLOYEE AS E JOIN ASSIGNMENT AS A
ON E.EmployeeNumber =
A.EmployeeNumber
JOIN PROJECT AS P
ON A.ProjectID = P.ProjectID;
KROENKE and AUER - DATABASE CONCEPTS (3rd Edition)
© 2008 Pearson Prentice Hall

17. Using SQL Views: Hide complicated SQL syntax - Results
SELECT * FROM EmployeeProjectHoursWorkedView;
KROENKE and AUER - DATABASE CONCEPTS (3rd Edition)
© 2008 Pearson Prentice Hall

18. Using SQL Views: Layering Computations and Built-in Functions 1st SQL Statement
CREATE VIEW ProjectHoursToDateView AS
SELECT PPOJECT.ProjectID,
Name AS ProjectName,
MaxHours AS ProjectMaxHours,
SUM(HoursWorked) AS
ProjectHoursWorkedToDate
FROM PROJECT, ASSIGNMENT
WHERE PROJECT.ProjectID =
ASSIGNMENT.ProjectID
GROUP BY PROJECT.ProjectID;
KROENKE and AUER - DATABASE CONCEPTS (3rd Edition)
© 2008 Pearson Prentice Hall

19. Using SQL Views: Layering Computations and Built-in Functions 2nd SQL Statement
CREATE VIEW ProjectsOverAllotedMaxHoursView AS
SELECT ProjectID, ProjectName,
ProjectMaxHours,
ProjectHoursWorkedToDate
FROM ProjectHoursToDateView
WHERE ProjectHoursWorkedToDate > ProjectMaxHours;
KROENKE and AUER - DATABASE CONCEPTS (3rd Edition)
© 2008 Pearson Prentice Hall

20. Using SQL Views: Layering Computations and Built-in Functions Results
SELECT ProjectID, ProjectName, ProjectMaxHours,
ProjectHoursWorkedToDate,
(ProjectHoursWorkedToDate
- ProjectMaxHours)
AS HoursOverMaxAllocated
FROM ProjectsOverAllotedMaxHoursView
ORDER BY ProjectID;
KROENKE and AUER - DATABASE CONCEPTS (3rd Edition)
© 2008 Pearson Prentice Hall

21. End of Presentation on Appendix C
DAVID M. KROENKE and DAVID J. AUER
DATABASE CONCEPTS, 3rd Edition
End of Presentation on Appendix C
SQL Views