Fast and dirty code to show structure for a way to query on objects. Needs improvment for working with const and puting stuff in lists if chosen, and probably more.

db_query_structure_excample.cpp

#include "stdafx.h"
#include <string>

class collection {};


template<typename query_set_base_t>
struct query_set_base
{
	query_set_base_t & select(const std::string & q) { return *static_cast<query_set_base_t*>(this); }
	query_set_base_t & filter(const std::string & q) { return *static_cast<query_set_base_t*>(this); }
	query_set_base_t & order_by(const std::string & q) { return *static_cast<query_set_base_t*>(this); }
};
class query_set : public query_set_base<query_set> {};

template<typename query_set_t>
class query_manager_base
{
protected:
	query_set_t _query;

public:
	// from standard query set
	query_set_t & select(const std::string & q) { return _query.select(q); }
	query_set_t & filter(const std::string & q) { return _query.filter(q); }
	query_set_t & order_by(const std::string & q) { return _query.order_by(q); }

	// standard query manager functions
	void update() {};
	void insert() {};
};
typedef query_manager_base<query_set> query_manager;


template<typename query_manager_t>
struct model_base	// Table
{
	query_manager_t objects;

	void update() { objects.update(); }
	void insert() { objects.insert(); }
};

typedef model_base<query_manager> model;


//////////////////////////////////////////////////////////////////////

// Custom query managers and querysets

// Custom query set
struct custom_query_set : public query_set_base<custom_query_set>
{
	custom_query_set & get_special_users() { return *this; }
};

// custom query manager
struct custom_query_manager : public query_manager_base<custom_query_set>
{
	// From custom query set
	custom_query_set & get_special_users() { return _query.get_special_users(); }

	// Custom query manager functions
	void user(const std::string & client_no, collection & c) {}	
	void update() {}	// Custom update. like setting timestamps..
};

//////////////////////////////////////////////////////////////////////

// models / tables 
class user : public model {};
class customer : public model_base<custom_query_manager> {};


int main()
{

	user c;	// Has only out of the box functionality
	c.objects.select("UserNo = '1'");

	collection col;
	customer cdc;	// Has CUSTOM queryset and query manager functions
	cdc.objects.user("1", col);	// CUSTOM query function

	cdc.objects.
		select("").
		get_special_users().	// CUSTOM query for case_debt_collection
		filter("").
		order_by("");


	cdc.update();	// Calls CUSTOM update 
	cdc.insert();	// calls standard insert
	

	return 0;
}