sql views appendix e david m. kroenke and david j. auer database concepts, 6 th edition

SQL ViewsAppendix E

DAVID M. KROENKE and DAVID J. AUER

DATABASE CONCEPTS, 6th Edition

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of America.

Copyright © 2013 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

KROENKE and AUER - DATABASE CONCEPTS (6th Edition) Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall

E-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.


E-4

SQL CREATE VIEW Statement

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

CREATE VIEW ViewName AS {SQL SELECT statement};


E-5

SQL CREATE VIEW Example

CREATE VIEW EmployeePhoneView AS SELECT FirstName, LastName,

Phone AS EmployeePhone FROM EMPLOYEE;


E-6

Creating an SQL View:Microsoft SQL Server 2012


E-7

Figure E-1: Creating a View in the Microsoft SQL Server Management Studio

Creating an SQL View:Oracle Database 11g Release 2


E-8

Figure E-2: Creating a View in the Oracle SQL Developer

Creating an SQL View in:Oracle MySQL 5.5


E-9

Figure E-3: Creating a View in the MySQL Workbench

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 EmployeePhoneViewORDER BY LastName;


E-10

Using the EmployeePhoneView inMicrosoft SQL Server 2012


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Figure E-4:Using EmployeePhoneView in the Microsoft SQL Server Management Studio

Using the EmployeePhoneView inOracle Database 11g Release 2


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Figure E-5: Using EmployeePhoneView in the Oracle SQL Developer

Using the EmployeePhoneView in Oracle MySQL 5.5


E-13

Figure E-6: Using EmployeePhoneView in the MySQL Workbench

Some Uses for SQL Views


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

E-14

Using SQL Views: Hide columns or rows I

CREATE VIEW BasicDepartmentDataView AS SELECT DepartmentName,

Phone AS DepartmentPhone FROM DEPARTMENT;

SELECT * FROM BasicDepartmentDataViewORDER BY DepartmentName;


E-15

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;


E-16

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;


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Using SQL Views: Display results of computations – Results

SELECT * FROM ProjectHoursToDateViewORDER BY PROJECT.ProjectID;


E-18

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;


E-19

Using SQL Views: Hide complicated SQL syntax – Results

SELECT * FROM EmployeeProjectHoursWorkedView;


E-20

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;


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2nd SQL Statement

CREATE VIEW ProjectsOverAllotedMaxHoursView AS

SELECT ProjectID, ProjectName, ProjectMaxHours, ProjectHoursWorkedToDate

FROM ProjectHoursToDateView WHERE ProjectHoursWorkedToDate > ProjectMaxHours;


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Results

SELECT ProjectID, ProjectName, ProjectMaxHours, ProjectHoursWorkedToDate, (ProjectHoursWorkedToDate

- ProjectMaxHours) AS HoursOverMaxAllocated

FROM ProjectsOverAllotedMaxHoursViewORDER BY ProjectID;


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SQL ViewsEnd of Presentation on Appendix E

DAVID M. KROENKE and DAVID J. AUER

DATABASE CONCEPTS, 6th Edition

sql views appendix e david m. kroenke and david j. auer database concepts, 6 th edition

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