dr. chen, management information systems chapter 5 database processing jason c. h. chen, ph.d....

Dr. Chen, Management Information Systems

Chapter 5Database Processing

Jason C. H. Chen, Ph.D.Professor of MIS

School of Business AdministrationGonzaga UniversitySpokane, WA 99258

[email protected]


GearUp Scenarios

Chapter 5: Database Processing

• GearUp does not have the easy access to data needed to analyze vendor quality and costs

2


GearUp: “Can You Put the Data into Access?”

• GearUp needs operating data to analyze for cost-cutting decisions

• Need to extract and combine data from multiple systems

• Will use Access to create report• In general, what does GearUp need for improving

its decisions?• Answer - Database processing


• Businesses of every size organize data records into collections called databases. At one extreme, small businesses use databases to keep track of customers; at the other extreme, huge corporations such as Dell and Amazon.com use databases to support complex sales, marketing, and operations activities. In between, we have businesses like FlexTime that use databases as a crucial part of their operations, but they don’t have a trained and experienced staff to manage and support the databases. To obtain answers to the one-of-a-kind queries he needs, Neil needs to be creative and adaptable in the way that he accesses and uses his database.

• This chapter discusses the why, what, and how of database processing. We begin by describing the purpose of databases and then explain the important components of database systems. We then overview the process of creating a database system and summarize your role as a future user of such systems.

• Users have a crucial role in the development of database applications. Specifically, the structure and content of the database depends entirely on how users view their business activity. To build the database, the developers will create a model of that view using a tool called the entity-relationship model. You need to understand how to interpret such models, because the development team might ask you to validate the correctness of such a model when building a system for your use. Finally, we describe the various database administration tasks.

• This chapter focuses on database technology. Here we consider the basic components of a database and their functions. You will learn about the use of database reporting and data mining in Chapter 9.

Chapter Preview

4


Study Questions

Q1: What is the purpose of a database?

Q2: What is a database?

Q3: What are the components of a database application system?

Q4: How do database applications make databases more useful?

Q5: How are data models used for database development?

Q6: How is a data model transformed into a database design?

Q7: What is the users’ role in the development of databases?

Q8: 2022?


• What is the most important computer resource on the Internet

Search Engine (backend)?

?


• You will learn the following:– 1) Database Concepts and– 2) Conceptual Database Design (Data Model)

Answer: Database


Linking Internal Databases to the Web

DATABASE TRENDS

N 8

Server tierDatabase tierUser tier


Web-Based Client/Server Database Architecture

Network

Web server

Database Server

Web Browser5. Retrieved data

4. Data query

7. Data-based Web page

8. Data-based Web page

1. Request for data-based Web page

6. Retrieved data

3. Data query

2. Request for data-based Web page

LegendCommunicationsBetween Web browserAnd Web server

CommunicationsBetween Web serverAnd database server

9


TWO TYPES OF DATA PROCESSING

• FILE-BASED• DATA-BASED

10


Figure: File-based Approach to Data Processing

CheckingAccount

DataFiles

AutoLoanDataFiles

SavingsAccount

DataFiles

CheckingAccount

Programs

SavingsAccount

Programs

AutoLoan

Programs

11


Three file processing systems at a company

Duplicate Data

What is the main problem in the

company’s processing systems?


Disadvantages of File Processing

• Program-Data Dependence– All programs maintain metadata for each file they use

• Data Redundancy (Duplication of data)– Different systems/programs have separate copies of the

same data

• Limited Data Sharing– No centralized control of data

• Lengthy Development Times– Programmers must design their own file formats

• Excessive Program Maintenance– 80% of of information systems budget

13


Questions• Question-1: How to overcome most of the

problems from File-based data processing?• Answer: Data-based approach• Question-2: Is MS/Access a database?• Answer: No (Why?)• Question-3: Then, what is it?• You will learn all these concepts in the chapter.


Database Management System

?????? Databasecontainingcentralized

shared data

Application#1

Application#2

Application#3

15


Database Management System

DBMS manages data resources like an operating system manages hardware resources

DBMSDBMS Databasecontainingcentralized

shared data

Application#1

Application#2

Application#3

16


• As a database user, you play a crucial role in developing database applications for your business or organization.

• Organize and keep track of things• Keep track of multiple themes• General rule:

Single theme store in a ____________ Multiple themes require a __________

Q1: What Is the Purpose of a Database?

Fig 5-1 List of Student Grades, Presented in a Spreadsheet 17

databasespreadsheet


Student Data Form With Multiple Themes

Fig 5-2 Student Data Shown in a Form, from a Database

Dr. Chen, Management Information Systems 5-19

Q2: What is a database?• These are terms you’ll need to

know when working with databases. – A database is a self-describing

collection of integrated records

– A database is an organized collection of logically related data files. (different from the text)

– Bytes, characters of data, are grouped into columns which are also called fields.

– The fields are grouped into rows which are also called records.

– A table is a group of similar rows or records which is also called a file.

Fig 5-3 Student Table (also called a file)

19


Hierarchy of Data Elements

Fig 5-4 Hierarchy of Data Elements

This figure shows the hierarchy of data elements working from the smallest at the bottom to the largest at the top.

20


Components of a Database:Metadata Describes Structure of Database

Fig 5-5 Components of a Database

A database is more than just a group of tables. It includes tables or files plus the relationships among rows in the tables and metadata that describes the database’s structure.

21


Metadata

Fig 5-7 Sample Metadata (in Access)

Metadata are data that describe data and makes databases easy to use. Metadata is always a part of a database.

The Field Name, Data Type, and Description at the top of this diagram are part of the database’s metadata.

The additional

field properties

at the bottom

are also

considered

metadata.

Dr. Chen, Management Information Systems Fig. 5-6: Example of Relationships Among Rows

This diagram shows relationships among rows of different tables.

The Student Number value in the first row of the top table,1325, relates to the same Student Number value in a row in the second table.

What Are Relationships Among Rows?

23

Dr. Chen, Management Information Systems Fig. 5-6: Example of Relationships Among Rows

This diagram shows relationships among rows of different tables.

The Student Number value in the first row of the top table,1325, relates to the same Student Number value in a row in the second table.

Both that Student Number values and that of 4867 (and 1325) in the second table relate to those in the third.

What Are Relationships Among Rows?

24


• Key A column or group of columns that

identifies a unique row in a table. Student Number is the key of the Student

table. Given a value of Student Number, you can determine one and only one row in Student. Only one student has the number 1325.

Every table must have a (primary) key. Sometimes more than one column is

needed to form a unique identifier. In a table called City, for example, the key would consist of combination of columns (City, State) – form a composite key.

Email_Num is the key of Email Table. VisitID is the key of Office_Visit Table.

Relationship Special Terms

25

pk

pk

pk


• Foreign keys– These are keys of a different

(foreign) table than the table in which they reside.

– A relational database carries data in the form of tables and uses foreign keys to represent relationships

• Relational databases Relationships among tables

are created by using foreign keys.

• Relation Formal name for a table

Relationship Special Terms

26

pk fk

pk

pk fk

What is (are) the fk in this relation?


Study Questions








Q8: 2022?


• Applications make database data more accessible and useful. • Users employ a database application that consists of forms,

formatted reports, queries, and application programs. • Database management system (DBMS) processes database

tables for applications.

Q3: What Are the Components of a Database Application System?

Fig 5-8 Components of a Database Application System28


What Is a Database Management System (DBMS)?

• Database developers use the DBMS to create or modify tables, relationships, and other structures in a database.

• A DBMS (database management system) program is used to create, process, and administer a database.

• Popular DBMS products include:• Oracle from Oracle Corporation (World #1 Database company)• DB2 from IBM• Access from Microsoft (for personal computers)• SQL Server from Microsoft (for large computer systems)• MySQL, an open-source (it was acquired by Oracle) product that’s

license-free

• Don’t confuse a DBMS, which is a software program, with a database, which is a collection of tables, relationships and metadata. But, they are two different concepts.

29


• Database developers use the DBMS to create and modify tables, relationships, and other structures in the database.

• Below, the developer has added a new column called Response?. This new column has data type Yes/No.

Creating the Database and Its Structures

30Fig 5-9 Adding a New Column to a Table (in Access)


• Four DBMS operationsRead, _______, modify, _______ data

• Applications call DBMS in different waysFrom a form, when the user enters new or changed

data, a computer program behind the form calls the DBMS to make the necessary database changes.

From an application program, the program calls the DBMS directly to make the change.

Processing the Database

31

insert

delete


• SQL—“see-quell” International standard language for creating databases and

database structures, and processing databases • Used by most popular DBMS

• Following SQL statement inserts a new row into the Student table:

INSERT INTO Student([Student Number], [Student Name], HW1, HW2, MidTerm)

VALUES (1000, ’Franklin, Benjamin’, 90, 95, 100);

Structured Query Language (SQL)

32


• DBMS provides tools to assist in administration of the database.

• Used to set up a security system involving user accounts, passwords, permissions, and limits for processing the database

• Backing up database data, adding structures to improve performance of database applications, removing data no longer wanted or needed, and similar tasks

• Most organizations dedicate one or more employees to the role of database administration (as database administrator – DBA)

Administering the Database

33

http://en.wikipedia.org/wiki/DBMS


Major Responsibilities of Database Administration

34Fig 5-10 Summary of Database Administration Tasks


Study Questions








Q8: 2022?


Multi-User Processing Problem

• A database application includes forms, reports, queries, and applications programs available to one or more users.

• This figure depicts multi-user database processing. The system must be managed properly to avoid the following problems (called concurrent problems): Potential update loss because two users update same data at the same time Potential locking problems Possible data conflicts

• How to avoid these problems?

Fig 5-11 Use of Multiple Database Applications 36


Multi-User Processing Problem


• Lost-update problem Process A reads a customer record from a file containing account

information, including the customer’s account balance and phone number.

Process B now reads the same record from the same file so it has its own copy.

Process A changes the account balance in its copy of the customer record and writes the record back to the file.

Process B—which still has the original stale value for the account balance in its copy of the customer record—updates the customer’s phone number and writes the customer record back to the file.

Process B has now written its stale account balance value to the file, causing the changes made by process A to be lost.

(Source: http://en.wikipedia.org/wiki/File_locking)

Multi-User Processing Problem (another example)

38

http://dba.fyicenter.com/Interview-Questions/RDBMS-FUNDAMENTALS/RDBMS_FUNDAMENTALS_Lost_Update_Problem.html


What Are Forms, Reports, and Queries?

Reports show data in a structured context.

• Data entry forms are used to read, insert, modify, and delete data.

• Reports are used to show data in a structured context as the example to the right shows.

Fig 5-12 Example of a Student Report39


What Are Forms, Reports, and Queries?

Sample query form usedto enter phrase for search

Sample query results of query operation

A query form helps the user quickly find answers to questions. In this case, the words “barriers to entry” were found in Baker’s record.

Fig 5-13 (a) & (b) Sample Query and Results40


• Forms, reports, and queries work well for standard functions. However, most applications have unique requirements that a simple form, report, or query cannot meet.

• Application programs process logic that is specific to a given business need.

• Application programs serve as an intermediary between the Web server and database. Responds to events, such as when a user presses a

submit button; also reads, inserts, modifies, and deletes database data

Why Are Database Application Programs Needed?

41


Four Database Application Programs Running on a Web Server Computer

Fig 5-14 Four Application Programs on a Web Server Computer 42

• Database application programs process logic specific to a given business need. For example, a program could track backordered items and hold a customer order until the items are ready to ship.

• Application programs enable database processing over the Internet as the figure below shows. Users access the applications programs via a Web server, which in turn accesses a single DBMS and database.


• Enterprise DBMS Process large organizational and workgroup databases Support many, possibly thousands, of users and many different

database applications Support 24/7 operations and can manage databases that span

dozens of different magnetic disks with hundreds of gigabytes or more of data

IBM’s DB2, Microsoft’s SQL Server, and Oracle’s Oracle are examples of enterprise DBMS products.

• Personal DBMS Designed for smaller, simpler database applications Used for personal or small workgroup applications that involve

fewer than 100 users (normally fewer than 15), single user

Enterprise DBMS vs. Personal DBMS

43


Access: A DBMS and an Application Development Product

Before building a database, developers construct a logical representation of database data called a data model to describe the data and relationships to be stored in database.

• Here’s a comparison of an Enterprise DBMS versus a Personal DBMS. Enterprise DBMS

Large organizational and workgroup databases

Hundred to thousands of users

Many different database applications

24/7 operations Oracle, DB2, SQL Server

Personal DBMS Smaller, simpler applications Personal or small workgroup

applications 1 - 100 users Microsoft Access is both a

DBMS and application development product as this figure depicts.

44Fig 5-15 Personal Database System


PART II


Study Questions








Q8: 2022?


How to Design a Database?

• Questions: – What tables to create? (e.g., GU database)– What attributes should be included in each table?– How those tables are related to each other?

• Data model: is a conceptual representation of data classes (data files) and their relationships.

• Relational database: data are organized as two-dimensional tables called relations, which are linked together by sharing the same field.


Q5: How Are Data Models Used for Database Development?Database Development Process

A data model is similar to blueprints for a house. It’s a logical representation of database data that describes data and their relationships.

Fig 5-16 Database Development Process48


Steps of Database Development

User view-1 User view-2 User view-3

…

User view-N

Conceptual Schema (Model)

…

…

Logical Model(ERD or E/ERD)

Implementation(w/Physical or Internal Model)

User interview & Integrated Model

49


How are data models used for database development?

• Conceptual Design– The process of preparing an abstract model of the database

from business perspective, which describes the information needs of end users of the database

– Entity-relationship approach => E-R Diagram (ERD)– Relational DBMS:

• Transform ERD to tables• Normalization process (you will learn it later)

• Physical Design– Describe how data would be physically stored in the data

storage– Depends on the DBMS


• Entity-relationship (E-R) data modelEntity is another term for

Table File

A tool for constructing data models

Developers use it to describe the content of a data model by defining entities that will be stored in database and relationships among those entities

Unified Modeling Language (UML), less popular, tool for data modeling

What Is the Entity-Relationship Data Model?

51

http://en.wikipedia.org/wiki/Entity-relationship_model

http://en.wikipedia.org/wiki/Unified_Modeling_Language

http://en.wikipedia.org/wiki/Unified_Modeling_Language


• Some thing that the users want to track • Examples of entities:

Order, Customer, Salesperson, and Item. Some entities represent a physical object, such as Item or Salesperson; others represent a logical construct or transaction, such as Order or Contract.

Entity names are always singular.

• Attributes Describe characteristics of an entity. Examples: order attributes are OrderNumber, OrderDate, SubTotal,

Tax, Total, and so forth.

• Identifier (Key) An attribute (or group of attributes) whose value is associated with

one and only one entity instance.

Entities (Table or File)

52


How are data models used for database development?

• An entity-relationship (ER) data model helps developers define things (entities) that will be stored in the database as they are building a data model.

• It also defines relationships among those entities.• Entities are things users want to track. It can be a physical object

(inventory items) or a logical transaction (sales order). The names are always singular.

• Each entity has attributes that describe its characteristics. The entity “Order” has attributes like “OrderNumber” and “OrderDate”.

• An identifier (pk) is an attribute whose value is associated with one and only one entity instance. “OrderNumber” is the identifier for the “Order” entity because there should only be one number for each order. (see next slide)


Segment of an Enterprise Data Model

A Data Model on Customer and Order

CUSTOMER ORDER

Q1. One CUSTOMER normally places ___ ORDER?

Q2. One ORDER normally is placed by __ CUSTOMER?

How about the relationship between ORDER and PRODUCT?(see next slide)

1

M


Q3. One PRODUCT normally is contained in __ ORDER?

ORDER

ORDER_NUMBER (pk)

Customer_IDOrder_Date

Q4. One ORDER normally contains __ PRODUCT?M

M


(a) Segment of an Enterprise Data Model

Comparison of enterprise and project level data models

Q: what are two major differences between (a) & (b)?

(b) Segment of a Project-Level Data Model


Student Data Model Entities

Fig 5-17 Student Data Model Entities

Student, Department, Advisor, Email, and Office_Visit are the entity names in this model.

The entity identifiers are StudentNumber, DeptName, and AdvisorName. Not all entities require an identifier.

58

pk

pk

pk

pk?

pk?

Email_Number

Visit_ID


Entities with Relationships

• Relationships join one entity to another entity– One-to-one – 1:1– One-to-many – 1:N– Many-to-many – N:M

• This diagram shows that each Department Entity can have multiple Adviser Entities in a one-to-many relationship. Adviser Entities can have a many-to-many relationship with Student Entities.

59Fig 5-18 Examples of Department Adviser, and Student Entities and Relationships

1:N

M:N orN:M


Entity symbols

A special entity that is also a relationship

Relationship symbols

Basic E-R notation

Attribute symbols

60

Relationship degrees specify number of entity types involved Relationship

cardinalities specify how many of each entity type is allowed


Fig 5-19 Sample Relationship (Version 1)

Crow’s Feet1:N N:

M

N:M = many-to-many relationships

One adviser can have many students and one student can have many advisers.

1:N = one-to-many relationships

One department can have many advisers, but an adviser has at most one department.

61


Fig 5-20: Sample Relationships (Version 2)

Advisers may advise in more than one department, but a student may have only one adviser, representing a policy that students may not have multiple majors.

62

What is the main difference between V1 and V2


Crow’s-Foot Diagram Version

Fig 5-21 Sample Relationships Showing Maximum/Minimum Cardinality

Maximum cardinality represents the maximum number of entities that can be involved in a relationship.

Minimum cardinality represents the minimum number of entities that can be involved in a relationship.

The vertical bar below indicates that at least one entity is required between Department and Adviser and between Adviser and Student.

The oval below indicates that an entity is optional and doesn’t require a relationship.

63

mandatory optional


Study Questions








Q8: 2022?


• Database design is the process of converting a data model into tables, relationships, and data constraints.

• Database design team transforms entities into tables and expresses relationships by defining foreign keys.

• Two important database design concepts: normalization and the representation of two kinds of relationships.

• Normalization is a foundation of database design.• Representation of relationships will help you

understand important design considerations.

Database Design

65


How is a data model transformed into a database design?

Fig 5-22: Poorly Designed Employee Table

Converting a poorly structured table into two or more well-structured tables is called normalization (Normalization

The table below is poorly designed because it includes the DeptName as part of the Employee record, making it difficult to update.

It also creates data integrity

problems because

the DeptName is not

consistent throughout

the table after the

data were updated.

Question: What happen if “Smith” is laid off and the record is deleted?

66

http://dba.fyicenter.com/Interview-Questions/Data-Warehousing/What_is_Normalization_First_Normal_Form_Second.html




…User view-N


…

…


Implementation(w/Physical Model)

???

67




…User view-N


…

…


Implementation(w/Physical Model)

NORMALIZATION (up to 3NF) (more tables created)

User interview & Integrated Model

68


• In the right figures, some rows show Dept. 100 is “Accounting and Finance” and others show Dept. 100 is “Accounting.” Which one is correct?

• A table with data integrity problems will produce incorrect results and inconsistent information.

• Data integrity problems happen when data are duplicated.

• Users will lose confidence in the information, and system will develop a poor reputation. Information systems with poor reputations become serious burdens to the organizations that use them.

Data Integrity Problems

69


Normalizing for Data Integrity

• Normalized tables eliminate data duplication, but they can be slower to process.

• General goal of normalization is to construct tables such that every table has a single topic or theme so that the database will be more reliable and stable for a long period of time without further changes or redesign.

70

http://en.wikipedia.org/wiki/Database_normalization


• Normalizing the tables by splitting the Department data into a separate table, as shown below, allows each table to describe a single topic or theme. The tables have been transformed into a normal form.

• By eliminating the duplicate data, you eliminate data integrity problems. That’s called

normalizing for

data integrity.• Now, the department

name only needs to

be updated in one place

in the normalized tables.

Normalizing for Data Integrity

71

Why it is in a better status?Question: What happen if “Smith” is laid off and the record is deleted?

Fig 5-23: Two Normalized

Tables


Summary of Normalization:Representing Relationships

72

• This chart shows the necessary steps to transform a data model into a relational database design.

Fig 5-24 Transforming a Data Model into a Database Design

will learn more in bmis441 (for MIS

concentration)


• Database practitioners classify tables into various normal forms according to the kinds of problems they have.

• Transforming a table into a normal form to remove duplicated data and other problems is called normalizing the table.

• Normalization is just one criterion for evaluating database designs. Normalized designs can be slower to process, database designers sometimes choose to accept non-normalized tables. The best design depends on the users’ processing requirements.

Summary of Normalization

73

http://en.wikipedia.org/wiki/Normal_forms

http://en.wikipedia.org/wiki/Database_normalization


Steps for Transforming Data Model Into a Database Design

1. Construct Adviser table and Student tables with key fields (pk)

2. Represent relationships by adding foreign keys (fk)

3. Create new table for N:M relationships (only if the relationship is N:M)


Q/A

When using the relational model to represent data, one must ________.A) add a foreign key to one of the tablesB) have more than ten tables in the modelC) establish only N:M relationships between tablesD) use metadata instead of foreign keys

Answer:


Transforming Data Model Into a Database Design –Step 1: Construct Tables with Key fields ‘pk’

The figure on the left represents the relationship (1:N) between tables. The figure on the right shows a normalized table for each entity.

Figure 5-25 (a&b) Representing a 1:N Relationship

1. However, we should know that AdvserName is not a good pk as it may not be “unique”.2. What should be a good one?

pk pk


From Figure 5-25 (c) Representing a 1:N Relationship

Transforming Data Model Into a Database Design - Step 2: Adding fk

pk

fkpk

Dr. Chen, Management Information Systems 78

Fig 5-25: Representing a 1:N Relationship (in normalized form)

78

pk

pk

pk

pk

Step 1.

Step 2.add foreign key (fk)

fk

Transforming a Data Model into a Database Design: 1:N Relationship


Figure 5-26 (a&b) Incorrect Representation of N:M Relationship

Transforming Data Model Into a Database Design - Step 3: Create new table for N:M relationships

The previous relationship

is 1:N, therefore, it

does not need to

create a new table

Because it is not in Third Normal Form (3NF).

How?


AdviserNameEmail

AdviserStudentNumberStudentNameMidTerm

Student

AdviserNameEmail

AdviserStudentNumberStudentNameMidTerm

Student

AdviserNameStudentNumber

Adviser_Student

How to solve the M:N problem?

(intersection entity)

What is the pk in the new Table (Adviser_Student)?

Ans: AdviserName and StudentNumber together (cpk – composite key)

General Rule: One M:N relationship will be broken down into Two 1:M relationships.


How to solve the M:N problem?

pk pk

pk pk

pk

[1]

[2]

[3]

Finally, three tables are produced for the normalized form. Therefore, two tables originally in the data model and three tables are produced after the normalization.


How to solve the M:N problem?The Final Status

pk pk

What is the pk?

cpk (composite key)

[2]

[3][1]

Dr. Chen, Management Information Systems Fig 5-26: Representing an N:M Relationship 83

(intersection entity w/ cpk)

Steps 1&2.

Step 3.

pk

fkpk


• Users are the final judges of: What data the database should contain, How tables should be related.

• Users review data model to be sure it accurately reflects users’ view of the business. Mistakes will come back to haunt you.

• Easiest time to change database structure is during data modeling stage. Changing a relationship from one-to-many to many-to-many in a data model is simply a matter of changing the 1:N notation to N:M.

• User review of the data model is crucial.

Q7: What Is the Users’ Role in theDevelopment of Databases?

84


• Users are the final judges of: What data the database should contain, How tables should be related.

• Users review data model to be sure it accurately reflects users’ view of the business. Mistakes will come back to haunt you.

• Easiest time to change database structure is during data modeling stage. Changing a relationship from one-to-many to many-to-many in a data model is simply a matter of changing the 1:N notation to N:M.

• User review of the data model is crucial.

Q7: What Is the Users’ Role in theDevelopment of Databases?

85


From Data to Knowledge:How Can Organization Gain Competitive Advantage?

(Survive and Prosper in the Digital Economy)

Data process Information Quality Information

Accessible

Organizational Knowledge

SharableCollaborative

-As a productNOT byproduct

-As core intellectual capitalNOT merely a few smart employers

DecisionMakingAvailable

Reusable

CRMAccountingFinanceOperationsManufacturing

Externalcustomers

D. B.

D.B.:Structured: R-DBMSUnstructured: Document Mgt. Systems

context,experience

automate informate innovate

Useable

K.BD.W


Q8: 2022?

• Relational databases will look much different• Use of non-relational data stores, called

NoSQL will be more common• Major DBMS vendors lose out to open-source

products and shift focus to services supporting open source software like Bigtable, Dynamo, Cassandra?

• Database models will be very different


VIDEO

• Video: Software as a Service overview (2m15s)-BMIS235

88


• End of Chapter 5

dr. chen, management information systems chapter 5 database processing jason c. h. chen, ph.d....

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