[Boost-users] How to use multi index container?

Hi, I try to use multi index container.I have one problem.Please help me.Thanks struct TOrder { char szDate[9]; //date type int nID; // order id int nProductID; //product id double fPrice;// int nVol;// //other member … } // The unique key of TOrder struct is szDdate and nID. How I can typedef the composite_key and the multi_index_container? Thank you for your help. Best regards. Yuan