terminology - What is the purpose of a Data Access Layer? -

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i started project long time ago , created data access layer project in solution have never developed in it. purpose of data access layer? there sources learn more data access layer?

in 2 words: loose coupling

to keep code use pull data data store (database, flat files, web services, whatever) separate business logic , presentation code. way, if have change data stores, don't end rewriting whole thing.

these days, various orm frameworks kind of blending dal other layers. typically makes development easier, changing data stores can painful. fair, changing data stores pretty uncommon.


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