Chapter 9

   

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1:	State two major reasons why field specifications are important.
A1:	Field specifications are important for these reasons: They help establish and enforce field-level integrity. They help enhance overall data integrity. They compel you to acquire a complete understanding of the nature and purpose of the data in the database. They constitute the "data dictionary" of the database.
2:	What do you gain by establishing field-level integrity ?
A2:	Field-level integrity warrants the following: The identity and purpose of a field is clear, and all of the tables in which it appears are properly identified. Field definitions are consistent throughout the database. The values of a field are consistent and valid. The types of modifications, comparisons, and operations that can be applied to the values in the field are clearly identified.
3:	What are the three categories of elements in a field specification?
A3:	The three categories of elements within a field specification are general , physical , and logical .
4:	Name the three types of specifications.
A4:	The three types of specifications are Unique , Generic , and Replica .
5:	Why is it beneficial for you to compose a proper field description?
A5:	Composing a field description is extremely beneficial because it forces you (and everyone in the organization) to think carefully about the nature of the data that will be stored in the field.
6:	What does the Data Type element indicate ?
A6:	The Data Type element indicates the nature of the data that the field stores.
7:	What does the Character Support element indicate?
A7:	The Character Support element indicates the type of characters that a user can enter into a given field value.
8:	What is the purpose of the Display Format element?
A8:	The Display Format element governs the appearance of a field's value when it is displayed on a screen or printed within a document.
9:	What types of keys are indicated on a field specification?
A9:	The types of keys indicated on a field specification are non , primary , alternate , and foreign .
10:	True or False: A null represents a blank value.
A10:	False. Null does not represent a blankit represents a missing or unknown value.
11:	What is the significance of the Range of Values element?
A11:	The Range of Values element specifies every possible valid value for a field.
12:	What is the purpose of an Edit Rule?
A12:	An Edit Rule designates at what point in time a user can enter a value into a field and whether he can modify that value.
13:	What is the purpose of the Comparisons Allowed element?
A13:	The Comparisons Allowed element indicates the types of comparisons a user can apply to a given field value when he's retrieving information from the field.
14:	What is a value expression ?
A14:	A value expression is some form of operation involving field values, literal values, or a combination of both, and it returns a single value that you can then use for a comparison operation.
15:	When do you use a generic specification?
A15:	You use a generic specification for a field that serves as a template for other fields within the database.

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