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Table design screen Field name Data type Field size Other properties.

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Presentation on theme: "Table design screen Field name Data type Field size Other properties."— Presentation transcript:

1 Table design screen Field name Data type Field size Other properties

2 Datasheet View

3 Relationships screen Tables One-to-Many relationships

4 Elements of a database application Tables - for storing data Forms - screen layouts for entering and viewing data Queries - for asking questions about the data Reports - for printed output

5 To consider in table design Does the field identify items (eg customer name) or inform people about them? (eg age) or do both? (eg address) Which item is the unique identifier - the key? (cust no) What data type is appropriate for the field? (cust no = num, cust name = alp) What additional properties should the field have? (cust no: size = 3, required = yes) In creating fields:

6 Are these fields identifiers or informational? Electricity/gas company customer number. ID Bank account number. ID Book title in library catalogue. ID/INF Class mark of book in library. ID/INF Date your overdue book or bill is due. INF Current level of funds in your account. INF Module name: e.g. Information Systems Development and Practice 1. ID/INF Module number: e.g. UQI114S1. ID/INF

7 Key fields Key fields uniquely identify each record in the table If no one field is a unique identifier then either: - create a new identifier (eg cust no) or -make a key from two or more fields (eg first name + second name)


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