lecture4 by taminulislam


									Designing The Database

        Lecture 4

                    Md. Ahsan – Ul - Hasan
          Designing the Database
1. Determine the purpose of the database.
2. Determine how the information should be divided among
   tables.(finding the Entities)
3. Determine the fields to contain the individual facts about
   the subject.(finding the fields)
4. Be sure each table has a field that will contain a unique
   value.(primary key)
5. Determine how the table will relate to one another.
6. Thoroughly review the design and steps through procedures
   with users.
7. Create the table structures in accordance with the design
   and enter data.
       Designing the Database

• Normalization:
      The process of creating small, stable, yet flexible and
      adaptive data structures from complex group of data is
      called normalization.
            Designing the Database
 Order      Order          Part                Part    Unit            Part
number      Date          Number              Name     Price         Quantity

Supplier     Supplier           Supplier
Number        Name              Address

Part                                                  Line Item

  Part       Part       Unit       Supplier            Order       Part      Part
 Number     Name        Price      Number             number      Number   Quantity

Supplier                                               Order
 Supplier   Supplier     Supplier                       Order      Order
 Number      Name        Address                       number      Date
                 ER Model
   • Things which can be distinctly indentified.

   • An association among entities.
          • one to one
          • one to many
          • many to many
            ER Model

Supplier   Parts   Line Item   Supplier
  Database Management Systems
• Data type:
  – Text (can contain any combination of characters
    and/or numbers. Up to 255)
  – Memo (use to store long text)
  – Number
  – Currency
  – AutoNumber
  – Date/Time
  – Yes/No
  – OLE Object
  – Hyperlink

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