66 Part I EXAM PREPARATION Entity and
66 Part I EXAM PREPARATION Entity and attribute names should not exceed 128 characters because a table in SQL Server is restricted to that. In fact, names should be kept as small as possible while still providing a meaningful object title. Remember, entities will become tables in SQL Server. Entity names should be unique. Attributes within the same entity should not be the same as any other object name; any naming in SQL Server should be kept unique. Chapter 3 goes into more detail on this point. Appropriate naming conventions are often developed as a corporate or development standard within an organization. Often mechanisms for shortening names or using common prefixing or suffixing may all be part of a programming team s standard. Attribute Makeup Now that you understand how to properly name attributes, it s time to look at how to break attributes down, a process more commonly known as decomposing attributes. Decomposing an attribute takes an attribute from its original form and divides it into its components. A good example of this is the breaking down of the Address attribute. An Address attribute may easily be broken down into attributes that store data as follows: Street. Stores the street address of the user. City. Stores where the user lives. State. Stores which state the user lives in. Zip. Stores the user s zip code. This process of decomposing an attribute helps you develop a normalized database structure as defined later in this chapter during the discussion of the physical design. Decomposing is also a function of usage as well. If, for example, a person s name is only needed in its full form, then a decision may be made to not break it up into the separate attributes of first and last name. Decomposing an attribute provides many benefits in contrast to general, built attributes that are not decomposed. First off, data integrity is improved. Data integrity is a measurement of how well data is kept consistent and flawless throughout the whole ER model.
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