Microsoft Access 3A: Primary Key / Import and Export: Import Text File, Export Data

Primary Keys:

• You have covered primary keys in section 2 - they are fundamental in database design.
• A primary key is a field that has a unique field (eg. StudentNumber-no two students have the same student number)
• Common examples of primary keys in a business database would include a customer number (no two customers would have the same number assigned to them).

School Example:

• The school database you will be working on will be used to keep track of textbooks signed out to students,
• Book titles should be a primary key, to prevent someone from entering in variations of a title
  • eg. if a book title was English Dictionary 3rd Ed. someone may enter the following:
    • Eng. Dict. 3d edition
    • English Dictionary 3
    • English Dictionary 3 rd edition
• Problems:
• If some books are entered in as Eng. Dict. 3d edition and others as English Dictionary 3 problems would arise when looking for copies of this book
• Consistancy refers to using the "exact same" name for fields
Example:

Movie Store Database:

The movie store database you will be working on will be used to keep track of movies (video/dvd's) signed out to customers.

• MovieTitles should be a primary key, to prevent someone from entering in variations of a title
  • eg. if a movie title was Charlie's Angels someone may enter the following:
• Charly's Angels
• Charlies Angels
• Charlys Angels
• Problems:
  • If movies are entered with slightly different titles problems will occur

Importing:

Sometimes you may be able to get data into your database without actually typing in each entry.

Example: if you were starting a new Access database in a school, the school will likely have all the records of students in some other program.

Instead of keying in each entry (think of the work for 1500 students!) you may be able to import the data into Access.

Most software programs (other kinds of databases, and other software such as spreadsheets etc.) allow the user to export the data, which can then be imported into another program.

Exporting:

In order to import data into Microsoft Access from another program, the other program has to be able to export the data.

Microsoft Access also allows you to export data that can be used in other programs.

Exported data can be viewed in NotePad, it is simply a file with all the names of students, grades etc. in the case of a student database.

Exported data files usually have a much smaller size, and are useful for storing backup data.

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