1. Planning a Database
© EIT, Author Gay Robertson, 2019

2. The 3 steps to planning …
Step one determine the purpose by looking at the brief
Step two determine the fields, the fieldnames (no spaces in fieldnames), the field sizes (estimate or work out an average size, by looking at data), determine the data types by looking at the brief
Step three determine the primary key field – look at the facts – find the fact that cannot be duplicated

3. Determine the purpose …
Decide the purpose of the database by looking at the brief (the brief is the list of everything that needs to be included in the database and everything that needs to be produced from the database)

4. Purpose …
The purpose of the database is to set up an inventory for the Taradale Cake Shop

5. Determine the fields, fieldnames and data types
Decide what facts you need to keep track of by reading the brief

6. Fields ….. The facts needed will be your Fields
Record these fieldnames in your Plan
Plan
Plan of Action:
Fieldname
ItemNo
Item
Quantity
Price
Dept
Fieldnames should have NO SPACES in them. They can be abbreviated eg Quan for Quantity

7. Data types ….. Decide what type of data will be stored in each field
Look at the data on the form that is filled in now

8. Look at the data types you will need
Short Text (alpha, numeric)
Numbers, (numbers used for calculations, so NOT phone numbers)
Currency
1 2.5% 32.7

9. There are other data types also ….
Autonumber
This allows a unique number to be attached to each record
You can set the number to increment eg 1, 2, 3, 4
An Autonumber is often used as a Record ID No

10. Date / Time
This allows you to display a date in the format needed eg 1/11/2017
Or display a time in the format needed eg 22:10

11. Yes/No or logical data type
Hyperlink to the Web

12. Data types ….. Record the data type for each field in your Plan Plan
Fieldname
ItemNo
Item
Quantity
Price
Dept
Data type
AutoNo
ShortText
Number
Currency

13. Field size …….
Field size is important if you have a lot of Short text data type fields in your database
By default (or automatically) Access sets Short text data type field size at 255 spaces

14. Why is field size important?
If the field size is too big, then it makes the database work slowly when finding records eg looking for Mr Gascoigne-Brown
It can increase the file size of the database and therefore waste your storage space eg if you allow 255 spaces for every persons name, and then you find most names are 5 letters you are wasting 250 spaces IN EVERY RECORD. How does that work? If you have 100 people in your database, each has a record, so 100 * 250 spaces = 25,000 extra storage spaces!

15. Deciding on your field sizes …..
If you already had your data in front of you you could count how many letters were in the longest name eg Gascoigne-Brown BUT generally, you don’t have all the data in front of you, so you need to use an “average” field size
For a first name, average about 20
For a last name, average about 30
For an address eg 19 Elliott St, average about 30
For a suburb eg Taradale, average about 20
For a City eg Palmerston North, average about 30

16. Determine the primary key …..
Decide if there is a fact that cannot be duplicated – this is known as a unique fact - this will be your primary key
Add this to your Plan
Now it is complete you can start creating your table
Plan
Data type
AutoNo
ShortText
Number
Currency
Fieldname
ItemNo
Item
Quantity
Price
Dept

17. Now what did I do to complete my plan???

18. What you did to complete your Plan ….
Step one: you determined the purpose of your database
Step two: you determined the fields, fieldnames, data types and field sizes
Step three: you determined the primary key

19. I need to read the brief in the workbook now and see if I can complete a plan!!