SQL Views Chapter 3A DAVID M. KROENKE and DAVID J. AUER DATABASE CONCEPTS, 5 th Edition

SQL ViewsChapter 3A

DAVID M. KROENKE and DAVID J. AUER

DATABASE CONCEPTS, 5th Edition

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means,

electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the publisher. Printed in the United States

of America.

Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall

Appendix Objectives

• Learn basic SQL statements for creating views

• Learn basic SQL statements for using views

• Understand the reasons for using views

3A-3KROENKE and AUER - DATABASE CONCEPTS (5th Edition) Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall

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


SQL CREATE VIEW Statement

• The SQL CREATE VIEW statement is used to create view structures.

CREATE VIEW ViewName AS

{SQL SELECT statement};


SQL CREATE VIEW Example

CREATE VIEW EmployeePhoneView AS

SELECT FirstName, LastName,

Phone AS EmployeePhone

FROM EMPLOYEE;


Creating an SQL View inSQL Server 2008 R2


Creating an SQL ViewMySQL 5.1


Creating an SQL View-Equivalent Query in

Microsoft Access 2010


Using an SQL SELECT Statement

• 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;


Using the EmployeePhoneView in SQL Server 2008 R2


Using the EmployeePhoneView in MySQL 5.1


Using an SQL View-Equivalent Query in

Microsoft Access 2010 I



Microsoft Access 2010 II



Microsoft Access 2010 III


Some Uses for SQL Views

• Hide columns or rows• Display results of computations• Hide complicated SQL syntax• Layer built-in functions

C-16KROENKE and AUER - DATABASE CONCEPTS (5th Edition) Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall

Using SQL Views: Hide columns or rows I

CREATE VIEW BasicDepartmentDataView AS SELECT DepartmentName,

Phone AS DepartmentPhone FROM DEPARTMENT;

SELECT * FROM BasicDepartmentDataViewORDER BY DepartmentName;


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 MarkingDepartmentProjectViewORDER BY ProjectID;


Using SQL Views: Display results of computations – SQL Statement

CREATE VIEW ProjectHoursToDateView ASSELECT PROJECT.ProjectID,

Name AS ProjectName,MaxHours AS ProjectMaxHours,SUM(HoursWorked) AS ProjectHoursWorkedToDate

FROM PROJECT, ASSIGNMENTWHERE PROJECT.ProjectID =

ASSIGNMENT.ProjectIDGROUP BY PROJECT.ProjectID;


Using SQL Views: Display results of computations – Results

SELECT * FROM ProjectHoursToDateViewORDER BY PROJECT.ProjectID;


Using SQL Views: Hide complicated SQL syntax – SQL Statement

CREATE VIEW EmployeeProjectHoursWorkedView ASSELECT Name, FirstName, LastName,

HoursWorkedFROM EMPLOYEE AS E JOIN ASSIGNMENT AS A

ON E.EmployeeNumber =A.EmployeeNumber

JOIN PROJECT AS PON A.ProjectID =

P.ProjectID;


Using SQL Views: Hide complicated SQL syntax – Results

SELECT * FROM EmployeeProjectHoursWorkedView;


Using SQL Views: Layering Computations and Built-in Functions

1st SQL Statement

CREATE VIEW ProjectHoursToDateView ASSELECT PPOJECT.ProjectID,

Name AS ProjectName,MaxHours AS ProjectMaxHours,SUM(HoursWorked) AS

ProjectHoursWorkedToDateFROM PROJECT, ASSIGNMENTWHERE PROJECT.ProjectID =

ASSIGNMENT.ProjectIDGROUP BY PROJECT.ProjectID;



2nd SQL Statement

CREATE VIEW ProjectsOverAllotedMaxHoursView AS

SELECT ProjectID, ProjectName, ProjectMaxHours, ProjectHoursWorkedToDate

FROM ProjectHoursToDateView WHERE ProjectHoursWorkedToDate > ProjectMaxHours;



Results

SELECT ProjectID, ProjectName, ProjectMaxHours, ProjectHoursWorkedToDate, (ProjectHoursWorkedToDate

- ProjectMaxHours) AS HoursOverMaxAllocated

FROM ProjectsOverAllotedMaxHoursViewORDER BY ProjectID;


SQL ViewsEnd of Presentation on Chapter 3A

DAVID M. KROENKE and DAVID J. AUER

DATABASE CONCEPTS, 5th Edition

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means,

electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the publisher. Printed in the United States

of America.

Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall

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SQL Views Chapter 3A DAVID M. KROENKE and DAVID J. AUER DATABASE CONCEPTS, 5 th Edition