1. RELATIONAL DATABASE MODEL
Database – logical collection of information you organize and access according to the logical structure of the information
Relational database – uses a series of two-dimensional tables or files to store information in the form of a database
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2. Databases Are… Collections of information
Created with logical structures
With logical ties within the information
With built-in integrity constraints
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3. Databases – Collections of Information
Databases have many tables
Solomon Enterprises as a concrete provider. Tables include:
Order
Customer
Concrete Type
Employee
Truck
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4. Databases – Collections of Information
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5. Databases – Created with Logical Structures
In databases, row numbers are irrelevant
In databases, columns have logical names such as Order Date and Customer Name
Data dictionary – contains the logical structure of the information in a database
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6. Databases – Logical Ties within the Information
Logical ties must exist between the tables
Logical ties are created with primary and foreign keys
Primary key – field (or group of fields in some cases) that uniquely describe each record
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7. Databases – Logical Ties within the Information
Foreign key – primary key of one file that appears in another file
Foreign keys help create relationships among tables
Table = file = relation (don’t confuse yourself)
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8. Databases – Logical Ties within the Information
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9. Databases – Built-in Integrity Constraints
Integrity constraint – rule that helps ensure the quality of information
Examples
Primary keys must be unique
Foreign keys cannot be blank
Sales price cannot be negative
Phone numbers must have an area code
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10. DBMS TOOLS
Database management system (DBMS) – helps you specify the logical organization for a database and access and use the information within a database
Word processing software = document
Spreadsheet software = workbook
DBMS software = database
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11. DBMS TOOLS 5 software components DBMS engine Data definition subsystem
Data manipulation subsystem
Application generation subsystem
Data administration subsystem
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12. DBMS TOOLS McGraw-Hill
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13. DBMS Engine
DBMS engine – accepts logical requests, converts them into their physical equivalent, and accesses the database and data dictionary
DBMS engine separates the logical from the physical
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14. DBMS Engine
Physical view – how information is arranged, stored, and accessed on a storage device
Logical view – how you (knowledge worker) need to arrange and access information
Databases – you work only with logical views
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15. Data Definition Subsystem
Data definition subsystem – helps you create and maintain the data dictionary and define the structure of the files in a database
Must create data dictionary for a database before entering any information
Extended Learning Module J covers this
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16. Data Manipulation Subsystem
Data manipulation subsystem – helps you add, change, and delete information
Primary interface between you and a database
Views
Report generators
QBE tools
SQL
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17. Views View – allows you to see the contents of a database file
Similar to a spreadsheet view
Make changes
Sort
Query
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18. Views Sort Find Add a new record McGraw-Hill
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19. Report Generators
Report generator – helps you quickly define formats of reports and what information you want to see in a report
Save report formats to use later
Uses a wizard interface
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20. Report Generators Specify the fields you want in a report
Specify the layout of the report
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21. Report Generators McGraw-Hill
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22. QBE Tools
Query-by-example (QBE) tool – helps you graphically design the answer to a question
“What driver most often delivers concrete to Triple A Homes?”
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23. QBE Tools
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24. SQL
Structured query language (SQL) – standardized fourth-generation language found in most DBMSs
Performs same task as QBE
Uses sentence structure instead
Mostly used by IT people
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25. Application Generation Subsystem
Application generation subsystem – contains facilities to help you develop transaction-intensive applications
Data entry screens (called forms in Access)
Programming languages
Mostly used by IT people
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26. Data Administration Subsystem
Data administration subsystem – helps you manage the overall database environment
Backup and recovery
Security management
Query optimization
Concurrency control
Change management
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27. Data Administration Subsystem
Backup and recovery
Periodically back up information
Recover a database after a failure
Security management
Who has access to what information
Who can perform CRUD tasks on information
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28. Data Administration Subsystem
Query optimization
Restructure physical view to optimize response times to queries
Concurrency control
What happens if two people simultaneously try to change the same information?
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29. Data Administration Subsystem
Change management
What is the effect of structural changes to a database?
What if you add a new column?
What happens if you delete a column?
What happens if you change a column’s attributes?
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