I work with PL/SQL at work and C++ at school... I have NEVER heard of a C++ Database. Do you mean the STL (Standard Template Library)? A little more info would be appreciated.
Here is one I know of. That is unless I am missing the boat on what you are asking for (would not be the first time found guilty of that). This is not the database I would choose to build an MRP system with, although they exist.
http://www.classicsoftware.com/prod04.htm
If you are wanting to create a database engine, from scratch, in C++, salute. I can tell you the major players, but not knowing the level of complexity you require, this is going to be a little vague.
You will need at least two files, but usually three. One will store your schema, next stores the data and the optional third stores the indexes. The files will have something like this:
Schema (minimum entries)
Table Name
List of Columns (attributes), data types, etc
First Data Row ID (very important)
Data Table (minimum entries)
Previous Row Pointer (long integer or single) - default 0 for 1st row
Current Row Pointer (long integer or single) - cannot be 0 or null
Next Row Pointer (long integer or single) - can be 0 (better) or null for EOF
Data in some delimited format
There are several indexing algorithms. I do not recall them off the top of my head.
Before I proceed any farther, is this the type of information you were seeking?