Presentation is loading. Please wait.

Presentation is loading. Please wait.

Dr. Chen, Oracle Database System (Oracle) 1 Chapter 13 Views (up to p.495) Jason C. H. Chen, Ph.D. Professor of MIS School of Business Gonzaga University.

Similar presentations


Presentation on theme: "Dr. Chen, Oracle Database System (Oracle) 1 Chapter 13 Views (up to p.495) Jason C. H. Chen, Ph.D. Professor of MIS School of Business Gonzaga University."— Presentation transcript:

1 Dr. Chen, Oracle Database System (Oracle) 1 Chapter 13 Views (up to p.495) Jason C. H. Chen, Ph.D. Professor of MIS School of Business Gonzaga University Spokane, WA USA

2 Dr. Chen, Oracle Database System (Oracle) 2 Objectives Create a view by using CREATE VIEW command or the CREATE OR REPLACE VIEW command Employ the FORCE and NOFORCE options State the purpose of the WITH CHECK OPTION constraint Explain the effect of the WITH READ ONLY option Update a record in a simple view Re-create a view

3 Dr. Chen, Oracle Database System (Oracle) 3 Objectives (continued) Explain the implication of an expression in a view for DML operations Update a record in a complex view Identify problems associated with adding records to a complex view Identify the key-preserved table underlying a complex view Drop a view Explain inline views and the use of ROWNUM to perform a “TOP-N” analysis Create a materialized view to replicate data

4 Dr. Chen, Oracle Database System (Oracle) 4 Database Views Table-1Table-NTable-2 database Single view table Query Output: Report, Graphs Database view A database view is a logical (virtual) table based on a query. It does not store data, but presents it in a format different from the one in which it is stored in the underlying tables. With the database view, you can view database records, but you can’t insert new records or modify or delete exiting records.

5 Dr. Chen, Oracle Database System (Oracle) 5 Views Permanent objects (logical or virtual table) that store queries but ____ data Based on a source query that: –can specify a subset of a single table’s fields or records –can join multiple tables Two purposes –Reduce complex query requirements –Restrict users’ access to sensitive data (enforce security; user has access to view but not underlying table) no

6 Dr. Chen, Oracle Database System (Oracle) 6 Creating and Using Database Views Views can be updateable if: –SELECT clause contains only fieldnames, no functions or calculations –Can ____ contain the ORDER BY, DISTINCT, or GROUP BY clauses, group functions, or set operators –search condition cannot contain a nested query Views are used like tables for selecting, inserting, updating and deleting data (only updatable views can be modified) not

7 Dr. Chen, Oracle Database System (Oracle) 7 Database View (cont.)  SELECT view_name FROM user_views;  SELECT view_name FROM ALL_VIEWS WHERE owner=‘SYSTEM’;  DROP VIEW ;  CREATE OR REPLACE VIEW AS ;

8 Dr. Chen, Oracle Database System (Oracle) 8 Types of Views Table 13-1 Overview of View Concepts

9 Dr. Chen, Oracle Database System (Oracle) 9 I. Creating a View You use the CREATE VIEW keywords to create a view Use OR REPLACE if the view already exists Use FORCE if the underlying table does not exist at the time of creation Provide new column names if necessary WITH CHECK OPTION constraint – if used, prevents data changes that will make the data subsequently inaccessible to the view WITH READ ONLY – prevents DML operations Figure 13-2 Syntax of the CREATE VIEW command

10 Dr. Chen, Oracle Database System (Oracle) 10 CREATE OR REPLACE VIEW book_vu AS SELECT isbn, title, category FROM books WHERE category = 'COOKING'; SELECT * FROM book_vu; SQL> SELECT * 2 FROM book_vu; ISBN TITLE CATEGORY COOKING WITH MUSHROOMS COOKING THE WOK WAY TO COOK COOKING See next slide for detailed process

11 Dr. Chen, Oracle Database System (Oracle) 11 FROM clause in query references a view rather than a table SELECT* FROM book_vu; BOOK_VU view (view stored in database) Processing steps: 1.A query references a view rather than a table in the FROM clause. 2.The query stored in the view is executed. 3.The results from the view query are stored in temporary storage. 4.The original query uses the temporary query results of the view as a table and completes execution. 2 Stores query: SELECT isbn, title, category FROM books WHERE category=‘COOKING’; Figure 13-1 View Processing

12 Dr. Chen, Oracle Database System (Oracle) 12 DML Operations on a Simple View Any DML operations are allowed through simple views unless created with WITH READ ONLY option DML operations that violate constraints on the underlying table are not allowed -- chapter 13, Figure 13-5; p.478 CREATE VIEW region_ne AS SELECT * FROM customers WHERE region = 'NE'; SELECT customer#, lastname, city, state, region FROM region_ne; -- chapter 13, Figure 13-4; p.477 CREATE VIEW inventory AS SELECT isbn, title, retail price FROM books WITH READ ONLY; SELECT * FROM inventory;

13 Dr. Chen, Oracle Database System (Oracle) 13 Why Failed to Update? -- chapter 13, Figure 13-6; p.479 UPDATE inventory SET price = WHERE title LIKE '%POEM'; -- “SELECT” is working (READ) SELECT * FROM inventory WHERE title LIKE '%POEM%'; UPDATE inventory SET title = 'THE SHORTEST POEMS' WHERE title LIKE '%POEM%'; Figure 13-6 Failed updates on the INVENTORY view SQL> UPDATE inventory 2 SET price = WHERE title LIKE '%POEM'; SET price = * ERROR at line 2: ORA-42399: cannot perform a DML operation on a read-only view ISBN TITLE PRICE SHORTEST POEMS SQL> UPDATE inventory 2 SET title = 'THE SHORTEST POEMS' 3 WHERE title LIKE '%POEM%'; SET title = 'THE SHORTEST POEMS' * ERROR at line 2: ORA-42399: cannot perform a DML operation on a read-only view

14 Dr. Chen, Oracle Database System (Oracle) 14 Combining Topics – VIEW and NON-Equality Join Combing both VIEW (chapter 13) and NON- EQUALITY JOINS (chapter 9; p.304) A non-equality join enables you to store a range's minimum value in one column of a record and the maximum value in another column. So instead of finding a column-to-column match, you can use a non-equality join to determine whether the item being shipped falls between minimum and maximum ranges in the columns. If the join does find a matching range for the item, the corresponding shipping fee (and others) can be returned in the results

15 Dr. Chen, Oracle Database System (Oracle) 15 Business Scenario Once a year, JustLee Books offers weeklong promotion in which customers receive a gift based on the value of each book purchase. If a customer purchases a book with a retail price of $12 or less, the customer receives a bookmark. If the retail price is more than $12 but less than or equal to $25, the customer receives a box of book-owner labels. For books retailing for more than $25 and less than or equal to $56, the customer is entitled to a free book cover. For books retailing for more than $56, the customer receives free shipping. SQL> SELECT * FROM promotion; GIFT MINRETAIL MAXRETAIL BOOKMARKER 0 12 BOOK LABELS BOOK COVER FREE SHIPPING

16 Dr. Chen, Oracle Database System (Oracle) 16 Task … Your job is to produce a report listing book title, publisher name, profit and its gift (note individual gift that is based on the retail price falls between minimal and maximal retail prices) Hint: Because the rows in the BOOKS and PROMOTION tables don't contain equivalent values (pk and fk), you must use a non-equality join to determine which gift a customer receives during the promotion.

17 Dr. Chen, Oracle Database System (Oracle) First Create VIEW for ‘book’ and publisher CREATE OR REPLACE VIEW book_profit_vu AS SELECT b.title, pu.name Publisher_Name, b.retail, b.retail-b.cost Profit FROM books b, publisher pu WHERE b.pubid = pu.pubid; SQL> SELECT * FROM book_profit_vu; TITLE PUBLISHER_NAME RETAIL PROFIT REVENGE OF MICKEY PRINTING IS US HOW TO MANAGE THE MANAGER PRINTING IS US E-BUSINESS THE EASY WAY PUBLISH OUR WAY BUILDING A CAR WITH TOOTHPICKS PUBLISH OUR WAY HOLY GRAIL OF ORACLE AMERICAN PUBLISHING DATABASE IMPLEMENTATION AMERICAN PUBLISHING HANDCRANKED COMPUTERS AMERICAN PUBLISHING COOKING WITH MUSHROOMS READING MATERIALS INC THE WOK WAY TO COOK READING MATERIALS INC HOW TO GET FASTER PIZZA READING MATERIALS INC BODYBUILD IN 10 MINUTES A DAY READING MATERIALS INC PAINLESS CHILD-REARING REED-N-RITE BIG BEAR AND LITTLE DOVE REED-N-RITE SHORTEST POEMS REED-N-RITE rows selected.

18 Dr. Chen, Oracle Database System (Oracle) use "NON-EQUALITY JOIN" (p.304) SELECT title, Publisher_name, retail, p.gift, TO_CHAR(profit, '$999.99') Proft FROM book_profit_vu bpvu, promotion p WHERE bpvu.retail BETWEEN p.minretail AND p.maxretail ORDER BY profit; column title format A23 COLUMN name format A18 column proft format $ column retail format $ column gift format A13 SELECT title, Publisher_name, retail, p.gift, TO_CHAR(profit, '$999.99') Proft FROM book_profit_vu bpvu, promotion p WHERE bpvu.retail BETWEEN p.minretail AND p.maxretail ORDER BY profit;

19 Dr. Chen, Oracle Database System (Oracle) 19 TITLE PUBLISHER_NAME RETAIL GIFT PROFT HANDCRANKED COMPUTERS AMERICAN PUBLISHING $25.00 BOOK LABELS $3.20 BIG BEAR AND LITTLE DOV REED-N-RITE $8.95 BOOKMARKER $3.63 E COOKING WITH MUSHROOMS READING MATERIALS INC. $19.95 BOOK LABELS $7.45 REVENGE OF MICKEY PRINTING IS US $22.00 BOOK LABELS $7.80 THE WOK WAY TO COOK READING MATERIALS INC. $28.75 BOOK COVER $9.75 HOW TO GET FASTER PIZZA READING MATERIALS INC. $29.95 BOOK COVER $12.10 BODYBUILD IN 10 MINUTES READING MATERIALS INC. $30.95 BOOK COVER $12.20 A DAY HOW TO MANAGE THE MANAG PRINTING IS US $31.95 BOOK COVER $16.55 ER E-BUSINESS THE EASY WAY PUBLISH OUR WAY $54.50 BOOK COVER $16.60 SHORTEST POEMS REED-N-RITE $39.95 BOOK COVER $18.10 BUILDING A CAR WITH TOO PUBLISH OUR WAY $59.95 FREE SHIPPING $22.15 THPICKS DATABASE IMPLEMENTATION AMERICAN PUBLISHING $55.95 BOOK COVER $24.55 HOLY GRAIL OF ORACLE AMERICAN PUBLISHING $75.95 FREE SHIPPING $28.70 PAINLESS CHILD-REARING REED-N-RITE $89.95 FREE SHIPPING $ rows selected. GIFT MINRETAIL MAXRETAIL BOOKMARKER 0 12 BOOK LABELS BOOK COVER FREE SHIPPING

20 Dr. Chen, Oracle Database System (Oracle) 20 A Version without VIEW --1c.(TRADITIONAL JOIN; modified version from p.305) SELECT b.title, pu.name "Publisher Name", b.retail, p.gift, b.retail-b.cost proft FROM books b, publisher pu, promotion p WHERE b.pubid = pu.pubid AND b.retail BETWEEN p.minretail AND p.maxretail ORDER BY b.retail-b.cost;

21 Dr. Chen, Oracle Database System (Oracle) chapter 13, Figure 13-7; p.480 CREATE OR REPLACE VIEW inventory AS SELECT isbn, title, retail price FROM books; SELECT * FROM inventory WHERE title LIKE '%BODYBUILD%'; -- chapter 13, Figure 13-8; p.481 UPDATE inventory SET price = WHERE title LIKE '%BODYBUILD%'; SELECT * FROM inventory WHERE title LIKE '%BODYBUILD%'; SELECT * FROM books WHERE title LIKE '%BODYBUILD%'; DML Operations on a Simple View (continued)

22 Dr. Chen, Oracle Database System (Oracle) 22 Rule for DML operations As long as the view isn’t created with the WITH READ ONLY option and any DML operation is allowed if it doesn’t violate an existing constraint on the underlying table. You can add, modify, and even delete data in an underlying table as long as one of the following constraints doesn’t prevent the operation: –PRIMARY KEY - FOREIGN KEY –UNIQUE - NOT NULL –WITH CHECK OPTION Practice Figure 13-9 to (pp )

23 Dr. Chen, Oracle Database System (Oracle) 23 Exercises Practice all the examples in the text. A Script file is available on the Bb (file name: ch13Queries.sql) After completing all examples, do the HW. In-class Exercise # CREATE VIEW contact AS SELECT contact, phone FROM publisher;

24 Dr. Chen, Oracle Database System (Oracle) 24 Homework - Hands-On Assignments Read and Practice all examples on Chapters Read Oracle assignment and create a script file Oracle_ch13_Lname_Fname.sql for questions (#1-5 and 9,10; p.508) on “Hands-on Assignments”. 2. Execute and test one problem at a time and make sure they are all running successfully. 3. When you done, spool the script files (see next slide for spooling instructions) and UPLOAD script and spooled files (Oracle_ch13_Spool_Lname_Fname.txt) by the midnight before the next class. me with one attachment (Oracle_ch13_Spool_Lname_Fname.) to: with subject title of bmis441_Oracle_ch13 (or Bmis441-02_Oracle_ch13)

25 Dr. Chen, Oracle Database System (Oracle) 25 How to Spool your Script and Output Files After you tested the script file of Oracle_ch13_Lname_Fname.sql successfully, follow the instructions below to spool both script and output files: Step 0. Run the following script file from SQL*Plus (since you have created JLDB tables) 1. type the following on SQL> –Spool c:\oradata\Oracle_ch13B_Spool_Lname_Fname.txt (make sure your name is entered) 2. open Oracle_ch13_Lname_Fname.sql that you already tested 3. copy and paste all the SQL commands (including all comments) to the SQL*PLUS 4. type Spool Off on the SQL> The output should contain your personal information, all SQL commands and their solution on the.txt file and saved in C: drive (oradata\ folder) UPLOAD script and spooled files (*.sql and *.txt)

26 Dr. Chen, Oracle Database System (Oracle) 26 PART II

27 Dr. Chen, Oracle Database System (Oracle) 27 II. Creating a Complex View A complex view may contain data from multiple tables or data created with the GROUP BY clause, functions, or expressions Type of DML operations allowed depends on various factors

28 Dr. Chen, Oracle Database System (Oracle) 28 DML Operations on a Complex View with an Arithmetic Expression Figure Create and update a complex view named prices

29 Dr. Chen, Oracle Database System (Oracle) 29 Rule#1: DML operations are not permitted if the view includes a column based on arithmetic expression Figure Failed attempts to add a new book via the PRICES view -- chapter 13, Figure 13-15; p.488 INSERT INTO prices (isbn, title, cost, retail) VALUES( , 'A New Book', 8.95, 15.95);

30 Dr. Chen, Oracle Database System (Oracle) 30 Figure Constraint violation with an INSERT command via the PRICES view no pubid is inserted Rule#2: DML operations are not permitted if they violate a constraint such as NOT NULL, UNIQUE etc.

31 Dr. Chen, Oracle Database System (Oracle) 31 DML Operations on a Complex View Containing Data from Multiple Tables DML operations cannot be performed on non-key-preserved tables, but they are permitted on key-preserved tables Figure PRICES view with a table join Practice: Figure 13-18

32 Dr. Chen, Oracle Database System (Oracle) 32 DML Operations on a Complex View Containing Data from Multiple Tables (continued) Figure Failed attempt to update the publisher name via the PRICES view Rule#3: DML operations can’t be performed on a non- key- preserved table.

33 Dr. Chen, Oracle Database System (Oracle) 33 DML Operations on a Complex View Containing Functions or Grouped Data Rule#4: DML operations are not permitted if the view includes a group function or a GROUP BY clause, the DISTINCT keyword, or the ROWNUM pseudocolumn. Figure View including grouped data -- chapter 13, Figure 13-21; p.492 CREATE VIEW balancedue AS SELECT customer#, order#, SUM(quantity * retail) Amtdue FROM customers JOIN orders USING (customer#) JOIN orderitems USING (order#) JOIN books USING (isbn) GROUP BY customer#, order#; SELECT * FROM balancedue;

34 Dr. Chen, Oracle Database System (Oracle) 34 SELECT * FROM balancedue; Figure View including grouped data

35 Dr. Chen, Oracle Database System (Oracle) 35 DML Operations on a Complex View Containing Functions or Grouped Data (continued) Figure Failed DELETE command on a view with grouped data

36 Dr. Chen, Oracle Database System (Oracle) 36 Dropping a View Use DROP VIEW command Figure Command to drop the PRICES view

37 Dr. Chen, Oracle Database System (Oracle) 37 III. Creating an Inline View An inline view is a temporary table created by using a subquery in the FROM clause It can only be referenced while the command is being executed Most common usage – “TOP-N” analysis

38 Dr. Chen, Oracle Database System (Oracle) 38 “TOP-N” Analysis ORDER BY included to identify top values: –Descending for highest values –Ascending for lowest values Extract data based on ROWNUM –Up to “N” rows returned Figure Syntax of TOP-N analysis

39 Dr. Chen, Oracle Database System (Oracle) 39 “TOP-N” Analysis (continued) Figure TOP-N analysis to identify the five most profitable books

40 Dr. Chen, Oracle Database System (Oracle) 40 Figure TOP-N analysis to identify the five most profitable books Figure TOP-N analysis to determine the three lest profitable books

41 Dr. Chen, Oracle Database System (Oracle) 41 Exercises Practice all the examples in the text. A Script file is available on the Bb (file name: ch13Queries.sql) After completing all examples, do the HW. In-class Exercise # CREATE VIEW contact AS SELECT contact, phone FROM publisher;

42 Dr. Chen, Oracle Database System (Oracle) 42 Homework - Hands-On Assignments Read and Practice all examples on Chapters Read Oracle assignment and create a script file Oracle_ch13_Lname_Fname.sql for questions (#1-5 and 9,10; p.508) on “Hands-on Assignments”. 2. Execute and test one problem at a time and make sure they are all running successfully. 3. When you done, spool the script files (see next slide for spooling instructions) and the file (Oracle_ch13_Spool_Lname_Fname.txt) to me by the midnight before the next class. me with one attachment (Oracle_ch13_Spool_Lname_Fname.) to: with subject title of Bmis441-01_Oracle_ch13 (or Bmis441-02_Oracle_ch13)

43 Dr. Chen, Oracle Database System (Oracle) 43 How to Spool your Script and Output Files After you tested the script file of Oracle_ch13_Lname_Fname.sql successfully, follow the instructions below to spool both script and output files: Step 0. Run the following script file from SQL*Plus (since you have created JLDB tables) 1. type the following on SQL> –Spool c:\oradata\Oracle_ch13B_Spool_Lname_Fname.txt (make sure your name is entered) 2. open Oracle_ch13_Lname_Fname.sql that you already tested 3. copy and paste all the SQL commands (including all comments) to the SQL*PLUS 4. type Spool Off on the SQL> The output should contain your personal information, all SQL commands and their solution on the.txt file and saved in C: drive (oradata\ folder) me with the spooled file (.txt) with attachment to: with subject title of Bmis441-01_Oracle_ch13 (or Bmis441-02_Oracle_ch13)

44 Dr. Chen, Oracle Database System (Oracle) 44 PART III

45 Dr. Chen, Oracle Database System (Oracle) 45 Materialized Views Replicate data Store data retrieved from view query Referred to as “snapshots”

46 Dr. Chen, Oracle Database System (Oracle) 46 Materialized Views (continued) Figure Creating a materialized view named CUSTBAL_MV

47 Dr. Chen, Oracle Database System (Oracle) 47 Figure Query a materialized view

48 Dr. Chen, Oracle Database System (Oracle) 48 Materialized Views (continued) Figure Drop a materialized view

49 Dr. Chen, Oracle Database System (Oracle) 49 Summary A view is a temporary or virtual table that is used to retrieve data that exists in the underlying database tables The view query must be executed each time the view is used A view can be used to simplify queries or to restrict access to sensitive data A view is created with the CREATE VIEW command A view cannot be modified; to change a view, it must be dropped and then re-created, or the CREATE OR REPLACE VIEW command must be used

50 Dr. Chen, Oracle Database System (Oracle) 50 Summary (continued) Any DML operation can be performed on a simple query if it does not violate a constraint A view that contains expressions or functions, or that joins multiple tables, is considered a complex view A complex view can be used to update only one table; the table must be a key-preserved table Data cannot be added to a view column that contains an expression DML operations are not permitted on non-key-preserved tables

51 Dr. Chen, Oracle Database System (Oracle) 51 Summary (continued) DML operations are not permitted on views that include group functions, a GROUP BY clause, the ROWNUM pseudocolumn, or the DISTINCT keyword Oracle 11g assigns a row number to every row in a table to indicate its position in the table; the row number can be referenced by the keyword ROWNUM A view can be dropped with the DROPVIEW command; the data is not affected, because it exists in the original tables An inline view can be used only by the current statement and can include an ORDER BY clause “TOP-N” analysis uses the row number of sorted data to determine a range of top values Materialized views physically store view query results


Download ppt "Dr. Chen, Oracle Database System (Oracle) 1 Chapter 13 Views (up to p.495) Jason C. H. Chen, Ph.D. Professor of MIS School of Business Gonzaga University."

Similar presentations


Ads by Google