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10. Database

All Past Paper Questions: ...

Managmehnt Information Systems​

  • how efficiently?

    • provides past, present and prediction information
    • helps in decision making
    • MIS manager
      • analyses bussiness problems
      • designs and maintains computer applications
        • to solve organizations problems
      • helps with project management
    • used to create reports and charts
      • sales
      • inventory
      • production
    • reports provided at regular intervals
    • to help evaluvate companies performance
    • to spot trends in revenue growth

  • description

    • helps with decision making
    • help with project managment
    • gather and information about various aspects, like
      • personnel
      • sales
      • inventory
      • production
    • to create reports
    • to evaluvate company's performance
    • to compare reports (daily, weekly, monthly, anually)
    • to spot trends in revenue / growth / profit
    • to assist them in making predictions about company

Queries​

Static Parameter Query​

  • a query that is fixed
  • examples
    • search for John (static parameter query)
      • everytime, the query will search for first_name John
      • if want to search another name
        • open query in design view
        • change first_name to that name

Dynamic Parameter Query​

  • examples
    • search for John (dyanmic parameter query)
      • she can type different names
      • everytime the query is run
        • dialog box asks for first_name
        • or any other parameters
      • saves time of designing

Normalization​

Questions

  • pg. 4

0NF (Zero Normal Form)​

Description​

Also called "unnormlized" data

This is an unnormalized form where the table may contain duplicate rows and non-atomic (multi-valued) attributes.

Features​

  • No Structure: Data may be stored without any specific structure or constraints.
    • no Primary Key
  • Repeating Groups: Columns can contain sets or lists of values.
  • Redundancy: High potential for data redundancy and anomalies.

1NF​

Description​

A table is in 1NF if it has a primary key and all attributes are atomic (cannot divide).

Features​

  • Atomicity: Each column contains single, indivisible values (no lists or sets).
  • Primary Key: A unique identifier for each row, ensuring that all rows are distinct.
  • Fixed Number of Columns: The number of columns is fixed, and each column contains values of a single type.
  • No Repeating Groups: Data is organized into rows and columns, with no repeating groups or arrays.

2NF​

Description​

A table is in 2NF if it is in 1NF and all non-key attributes are fully functionally dependent on the entire primary key.

Features​

  • No Partial Dependency: Every non-key attribute is fully dependent on the whole primary key, not just part of it (important for tables with composite keys).
  • Elimination of Redundancy: Reduces redundancy by eliminating partial dependencies.
  • Improved Data Integrity: Ensures that updates, deletions, and insertions maintain consistency in the database.

3NF​

Description​

A table is in 3NF if it is in 2NF and all attributes are only dependent on the primary key, not on other non-key attributes.

Features​

  • No Transitive Dependency: Non-key attributes are independent of other non-key attributes, only depending on the primary key.
  • Minimal Redundancy: Further reduces redundancy by removing transitive dependencies.
  • Better Data Integrity: Simplifies the data structure and reduces the potential for anomalies during data manipulation.

Datatypes​

  • Date
    • description
      • can be in the form: mm/dd/yyyy
    • size
      • 3 bytes
  • Boolean
    • description
      • stores only 2 entries
        • 1 or 0
        • True or False
    • size
      • 1 byte
  • Text
    • description
      • when data consists of letters
    • size
  • Lookup Table
    • description
      • when only a limited number of options
    • size
  • Integers