16->The Data Mapper Pattern(etng预定)

16
The Data Mapper
Pattern
The two previous chapters―The Active Record Pattern and The Table Data Gateway Pattern―
showed strategies that abstract a table row and an individual table, respectively. While both
patterns are useful, each pattern’s implementation is closely coupled with the structure of the
underlying database, so solutions based on those patterns tend to be brittle. For instance, if your code
uses field names as keys in row arrays or attributes in row data objects, you’re application is tied to the
structure of the database and you may have to make extensive changes in PHP for every (relatively)
minor change in a table.
Because code and databases often change during development and evolve after they’re deployed,
there are real benefits to separating domain code and its database(s) as much as possible, insulating
each other from interdependencies and reducing the work required to realize a change in either.
The Problem
How can you minimize the coupling between your application’s classes and its database? For example,

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zlloveliuxin最近因为考试非常忙，所以改由etng翻译此章节。