July 2001
Beginner to intermediate
368 pages
6h 52m
English
book
Design Patterns Explained: A New Perspective on Object-Oriented Design
by Alan Shalloway, James R. Trott
Content preview from Design Patterns Explained: A New Perspective on Object-Oriented Design
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More Requirements for the Case Study
In the process of writing the application, suppose I get a new requirement to support both Oracle and SQL Server databases. Both of these systems are based on SQL (Structured Query Language), the common standard that makes it easier to use databases. Yet, even though this is a common standard at the general level, there are still differences in the details. I know that in general, when executing queries on these databases, I will use the following steps:
1. |
Format the CONNECT command.
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2. |
Send the database the CONNECT command.
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3. |
Format the SELECT command.
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4. |
Send the database the SELECT command.
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5. |
Return the selected dataset.
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The specific implementations of the databases differ, however, requiring ...