Database 6

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PremiereProducts_DatabaseConcepts.ppt
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Concepts of Database Management

Introduction to Database Management

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Objectives

  • Introduce Premiere Products, the company that is used as the basis for many of the examples throughout the text
  • Introduce basic database terminology
  • Describe database management systems (DBMSs)
  • Explain the advantages and disadvantages of database processing

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Premiere Products Background

  • Premiere Products
  • Distributor of appliances, houseware, and sporting goods
  • Uses spreadsheet software to maintain important data
  • Recent growth has made spreadsheet approach problematic

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Premiere Products Background (continued)

FIGURE 1-1: Sample orders spreadsheet

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Premiere Products Background (continued)

  • Problems using spreadsheet
  • Redundancy
  • Duplication of data or the storing of the same data in more than one place
  • Difficulty accessing related data
  • Limited security
  • Size limitations

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Premiere Products Background (continued)

  • Information Premiere Products needs to maintain
  • Sales Reps
  • Sales rep number, last name, first name, address, total commission, commission rate
  • Customers
  • Customer number, name, address, current balance, credit limit, number of customer’s sales rep
  • Parts Inventory
  • Part number, description, number units on hand, item class, warehouse number, unit price

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Premiere Products Background (continued)

FIGURE 1-2: Sample order

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Premiere Products Background (continued)

  • Items for each customer’s order
  • Order
  • Order number, order date, customer number
  • Order line
  • Order number, part number, number of units ordered, quoted price
  • Overall order total
  • Not stored because it can be calculated

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Database Background

  • Database
  • Structure that can store information about:
  • Different categories of information
  • Relationships between those categories of information
  • Entity
  • Person, place, object, event, or idea
  • Entities for Premiere Products: sales reps, customers, orders, and parts

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Database Background (continued)

  • Attribute
  • Characteristic or property of an entity
  • Example: Customer has name, street, city, etc.
  • May also be called a field or column
  • Relationship
  • Association between entities
  • One-to-many relationship
  • Each rep is associated with many customers
  • Each customer is associated with a single rep

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Database Background (continued)

FIGURE 1-3: Entities and attributes

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Database Background (continued)

FIGURE 1-4: One-to-many relationship

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Database Background (continued)

  • Data file
  • File used to store data
  • Computer counterpart to ordinary paper file
  • Database
  • Structure that can store information about:
  • Multiple types of entities
  • Attributes of those entities
  • Relationships between the entities

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Database Background (continued)

FIGURE 1-5: Sample data for Premiere Products

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Database Background (continued)

FIGURE 1-5: Sample data for Premiere Products (continued)

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Database Background (continued)

FIGURE 1-5: Sample data for Premiere Products (continued)

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Database Background (continued)

FIGURE 1-6: Alternative Orders table structure

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Database Background (continued)

  • Entity-relationship (E-R) diagram
  • Visual way to represent a database
  • Rectangles represent entities
  • Lines represent relationships between connected entities

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Database Background (continued)

FIGURE 1-7: E-R diagram for the Premiere Products database

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Database Management Systems

  • Database management system (DBMS)
  • Program, or collection of programs, through which users interact with a database
  • Popular DBMSs: Access, Oracle, DB2, MySQL, and SQL Server
  • Premiere Products decides to use Access
  • Database design
  • Determining the structure of the required database

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Database Management Systems (continued)

FIGURE 1-8: Using a DBMS directly

FIGURE 1-9: Using a DBMS through another program

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Database Management Systems (continued)

  • Forms
  • Screen objects used to maintain, view, and print data from a database
  • DBMS creates forms that Premiere Products needs
  • Reports
  • DBMS creates reports for Premiere Products based on user’s answers about the desired content and appearance of each report

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Database Management Systems (continued)

FIGURE 1-10: Part form

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Database Management Systems (continued)

FIGURE 1-11: Orders form

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Database Management Systems (continued)

FIGURE 1-12: Parts report

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Advantages of Database Processing

Getting more information from the same amount of data

Sharing data

Balancing conflicting requirements

  • Database administrator or database administration (DBA): person or group in charge of the database

Controlling redundancy

Facilitating consistency

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Advantages of Database Processing (continued)

Improving integrity

Integrity constraint: a rule that data must follow in the database

Expanding security

Security: prevention of unauthorized access

Increasing productivity

Providing data independence

  • Data independence: can change structure of a database without changing the programs that access the database

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Disadvantages of Database Processing

Larger file size

Increased complexity

Greater impact of failure

More difficult recovery

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