Parametrized ADO Stored Procedure from C++

[Ajaxx]

I’m trying to call a stored procedure on my SQL 2008 server with the below code. When I look at the query with the SQL profiler I get the following:

exec GetUserID @Email='[e-mail]',@Password='@Email'

What I expect to get is:

exec GetUserID @Email='[e-mail]',@Password='123456'

Can someone explain what is going on please?

#include "stdafx.h"
 
#import "C:\Program Files\Common Files\System\ado\msado15.dll" rename("EOF", "EndOfFile")
 
int _tmain(int argc, _TCHAR* argv[])
{
    try
    {
        ::CoInitialize(NULL);
 
        ADODB::_ConnectionPtr ConnectionPtr = NULL;
        ADODB::_CommandPtr CommandPtr = NULL;
        ADODB::_ParameterPtr ParameterPtr = NULL;
 
        char ConnectionString[200] = "Provider=SQLNCLI10; Server=IL47WS030501; Database=Demo; Trusted_Connection=yes;";
 
        ConnectionPtr.CreateInstance(__uuidof(ADODB::Connection));
 
        if(ConnectionPtr)
        {
            ConnectionPtr->Open(ConnectionString, "", "", 0);
        }
 
        CommandPtr.CreateInstance(__uuidof(ADODB::Command));
 
        if(ConnectionPtr && CommandPtr)
        {
            CommandPtr->ActiveConnection = ConnectionPtr;
            CommandPtr->CommandType = ADODB::adCmdStoredProc;
            CommandPtr->CommandText = _bstr_t("GetUserID");
            CommandPtr->NamedParameters = true;
 
            VARIANT vEmail;
            vEmail.vt = VT_BSTR;
            vEmail.bstrVal = _bstr_t("[e-mail]");
 
            VARIANT vPassword;
            vPassword.vt = VT_BSTR;
            vPassword.bstrVal = _bstr_t("123456");
 
            CommandPtr->Parameters->Append(CommandPtr->CreateParameter(_bstr_t("@Email"), ADODB::adVarChar, ADODB::adParamInput, sizeof(vEmail), vEmail));
            CommandPtr->Parameters->Append(CommandPtr->CreateParameter(_bstr_t("@Password"), ADODB::adVarChar, ADODB::adParamInput, sizeof(vPassword), vPassword));
 
            ADODB::_RecordsetPtr RecordsetPtr = CommandPtr->Execute(NULL, NULL, ADODB::adCmdStoredProc);
        }
 
        return 0;
    }
    catch(...)
    {
    }
}

[Ajaxx]

I don’t know the details of why but I was able to get it working using the following code without a VARIANT instead:

CommandPtr->Parameters->Append(CommandPtr->CreateParameter(_bstr_t("@Email"), ADODB::adVarChar, ADODB::adParamInput, 50, "[e-mail]"));
CommandPtr->Parameters->Append(CommandPtr->CreateParameter(_bstr_t("@Password"), ADODB::adVarChar, ADODB::adParamInput, 50, "123456"));