<p>I would like to implement a data access object pattern in C++, but preferably without using multiple inheritance and/or boost (which my client does not like). </p>

<p>Do you have any suggestions?</p>

OTL (otl.sourceforge.net) is an excellent C++ database library.  It's a single include file so doesn't have all the complexity associated (rightly or wrongly!) with Boost.
In terms of the DAO itself, you have many options.  The simplest that hides the database implementation is just to use C++ style interfaces and implement the data access layer in a particular implementation.
```
class MyDAO {
  // Pure virtual functions to access the data itself
}

class MyDAOImpl : public MyDAO {
  // Implementations to get the data from the database
}
```