User manual

Chapter 2
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Creating databases 41
For example, in the Clients table you might want to assign each client
a unique, identifying number. You wouldn’t enter a client
identification number into the table unless you had a new client to add,
so the existence of a client number determines the existence of a
record.
8. For each table, decide which fields will store data, and which ones
will be used from other (related) tables.
Each table has only one subject, and all fields in a table describe only
that subject.
For example, the fields in one record of the Clients table together store
all the information about one client.
Based on a table’s subject, you can see where it makes sense to store
the data and where to use data from a related table. Other than match
fields, all fields should appear only once in your database. Cross out
occurrences of fields that don’t pertain to the table’s subject.
9. Determine the relationships between the tables. In your plan, draw
a line from each match field in a table to the corresponding match field
in the related table.
What establishes a relationship between tables is that their match
fields contain matching data.
Client ID
Street
Postal Code
Client Name
City
Tour ID
Clients table
Routes table
Tour Name
Tours table
Phone
Route ID
Destination
Origin
Tour ID
Route ID
Destination
Tour Name
Origin
Client ID
Street
Postal Code
Client Name
City
Tour ID
Clients table
Routes table
Tour Name
Tours table
Phone
Route ID
Destination
Origin
Tour ID
Route ID
Destination
Tour Name
Origin