You therefore decide to add appropriate domains, so that you can later use them to specify data types for attributes when you create the entities. Titles (books, articles, and so on) can be up to 50 characters. Other identifiers are numeric, with up to 7 digits (no decimal places). Zip codes (United States postal codes) can be up to 10 characters ( nnnnn- nnnn).īook identifiers can be up to 20 characters. State codes (United States) are 2-character standard abbreviations. Street address lines can be up to 40 characters.
The first and last names of persons can be up to 25 characters each. In planning for your data needs, you have determined that several kinds of fields will occur in multiple kinds of records, and many fields can share a definition. You will perform the following major steps: (For information about the approaches, see Section 1.4, "Approaches to Data Modeling".) This simplified tutorial uses only a subset of the possible steps for the Top-Down Modeling approach.
If the instructions do not mention a particular dialog box, tab, or field, then do not specify anything for it. For more advanced tutorials and other materials, see Section 1.9, "Additional Resources for Data Modeling". The model is deliberately oversimplified and would not be adequate for any actual public or organizational library. This tutorial uses the same entities as for the tutorial provided with the SQL Developer online help. In this tutorial, you will use SQL Developer Data Modeler to create models for a simplified library database, which will include entities for books, patrons (people who have library cards), and transactions (checking a book out, returning a book, and so on). 2 Tutorial: Data Modeling for a Small Database
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