Circular include problem

[mesajflaviu]

I have entered into a circular include problem. I have a class:

#include "TestConnection.h"
#include "oci.h"
#include "SU_ORADB_imp.h"

class DBTestConnection final : public Connection
{
private:
	SU_ORADB_imp* imp_{ nullptr };
	bool m_connected = false;
	// methods
	DBTestConnection();
	// friend class
	friend ConnectionPoolFactory<DBTestConnection>;

public:
	bool heart_beat() override { return m_connected; }
	bool is_healthy() override { return m_connected; }
	void disconnect() override;
	bool connect() override;
	void do_something();
	~DBTestConnection() override;
	OCISvcCtx* GetServerContext() { return imp_->_svchp; }
};

and another class:

#pragma once

#include "oci.h"
#include "ConnectionFactory.h"

class SU_ORADB_imp
{
private:
	OCISvcCtx* _svchp;	// just for testing purpose
	// methods
	void Init();

protected:
	PoolProxy GetConnection();
	static std::unique_ptr<ConnectionPool> pool_;

public:
	void Connect();
	void Disconnect();
	SU_ORADB_imp();
	~SU_ORADB_imp();
	void DoSqlSelect();

	friend class DBTestConnection;
};

but I got these errors:

dbtestconnection.h(10): error C2143: syntax error: missing ';' before '*'
dbtestconnection.h(10): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
dbtestconnection.h(10): error C2334: unexpected token(s) preceding '{'; skipping apparent function body
dbtestconnection.h(24): error C2065: 'imp_': undeclared identifier

and

connectionfactory.h(11): error C2065: 'DBTestConnection': undeclared identifier
connectionfactory.h(12): error C2923: 'ConnectionPoolFactory': 'DBTestConnection' is not a valid template type argument for parameter 'T'
connectionfactory.h(27): error C2913: explicit specialization; 'ConnectionPoolFactory' is not a specialization of a class template

How can I get rid of this issue ? Can you help me a little bit ? I put here a test project to illustrate my problem.