[odb-users] Unresolved external symbol error when including *.hxx file with common declarations

[An Hu]

I must use the ODB framework in my project. I have 2 files: station.hxx and
common.hxx with following content:

common.hxx

#ifndef COMMON_HXX
#define COMMON_HXX
#include <string>
#pragma db value
struct ProcessAggregateName
{
#pragma db column("SHORTNAME")
 std::string SHORTNAME;
#pragma db column("LONGNAME")
 std::string LONGNAME;
#pragma db column("SECONDARYNAME")
 std::string SECONDARYNAME;
};
#pragma db value
struct Reporting
{
#pragma db column("OPERATIONALLOG")
 std::string OPERATIONALLOG;
#pragma db column("PRINTER")
 std::string PRINTER;
#pragma db column("HIGHLIGHTING")
 bool HIGHLIGHTING;
#pragma db column("REPORTTYPE")
 std::string REPORTTYPE;
};
#endif // COMMON_HXX

station.hxx

#ifndef STATION_HXX
#define STATION_HXX
#include <string>
#include "common.hxx"
#pragma db object table("STATION")
class station
{
public:
 station () {}
 #pragma db id column("ID")
 int ID;
 #pragma db column("OPERATINGDOMAIN")
 long OPERATINGDOMAIN;
 #pragma db column("NAME")
 ProcessAggregateName NAME;
 #pragma db column("EXPORTBASICDATA")
 bool EXPORTBASICDATA;
 #pragma db column("EXPORTPROCESSDATA")
 bool EXPORTPROCESSDATA;
 #pragma db column("IMPORTBASICDATA")
 bool IMPORTBASICDATA;
 #pragma db column("IMPORTPROCESSDATA")
 bool IMPORTPROCESSDATA;
 #pragma db column("REPORTING")
 Reporting REPORTING;
};
#endif // STATION_HXX

The reason for this: I want to use structures declared in common.hxx also
in other files, so I wanted to concentrate them in the same header file and
include it whereever I need them. My problem: if I do it this way, I get
linker errors like these:

 error LNK2019: unresolved external symbol "public: static void __cdecl
odb::access::composite_value_traits::bind(struct odb::mssql::bind *,struct
odb::access::composite_value_traits::image_type &,enum
odb::mssql::statement_kind)" (?bind@
?$composite_value_traits at UProcessAggregateName@@$03 at access@odb@
@SAXPAU0mssql at 3@AAUimage_type at 123@W4statement_kind at 43@@Z) referenced in
function "public: static void __cdecl
odb::access::object_traits_impl::bind(struct odb::mssql::bind *,struct
odb::access::object_traits_impl::image_type &,enum
odb::mssql::statement_kind)" (?bind@?$object_traits_impl at Vstation
@@$03 at access@odb@@SAXPAU0mssql at 3@AAUimage_type at 123@W4statement_kind at 43@@Z)
 error LNK2019: unresolved external symbol "public: static void __cdecl
odb::access::composite_value_traits::init(struct
odb::access::composite_value_traits::image_type &,struct
ProcessAggregateName const &,enum odb::mssql::statement_kind)" (?init@
?$composite_value_traits at UProcessAggregateName@@$03 at access@odb@
@SAXAAUimage_type at 123@ABUProcessAggregateName@@W4statement_kind at mssql@3@@Z)
referenced in function "public: static void __cdecl
odb::access::object_traits_impl::init(struct
odb::access::object_traits_impl::image_type &,class station const &,enum
odb::mssql::statement_kind)" (?init@?$object_traits_impl at Vstation
@@$03 at access@odb@@SAXAAUimage_type at 123@ABVstation@@W4statement_kind at mssql@3@
@Z)

If I copy the declaration of ProcessAggregateName and Reporting into
station.hxx directly instead of including common.hxx, everything goes fine.
What do I do wrong and how can I declare commonly used structures in a
single header and include it in multiple *.hxx files?