Is there a difference between the DAO pattern and the Data Mapper pattern? Is DAO just one of doing Data Mapper?
I wouldn't actually call DAO a "pattern". As I see it, DAO is pretty much what it is -- a Data Access Object", which encapsulates the details of accessing a persistent data store and generally speaking has nothing to do with the database:
interface IBlogDaoService
{
Blog GetBlog(long id);
void SaveBlog(Blog blog);
}
It's clear that implementations can use either DB (in which case it's quite logical to use a Data Mapper), or simple XML file storage mechanism.
The Data Mapper on the other hand is more of a pattern, which defines a layer responsible for translating in-memory graphs of objects to the relational structure.
来源：https://stackoverflow.com/questions/491938/whats-the-difference-between-dao-and-data-mapper