How to get just the key from a database ?

Question

Hello, the sample at FAQs was not enought to me...
My code to retrieve just the key (Exists this record ?).
//     Checks if the ticket exists in the database.
BOOL     CDSDBBD::TicExist(     char     *pcaTicCod)
     int          iResult;
     int          iLen;
     Dbt          dbtKey;
     Dbt          dbtData;
     char     caError[256];
     iLen     =     strlen(pcaTicCod);
     dbtKey     .set_data((void*) pcaTicCod);
     dbtKey     .set_size(iLen);
     dbtData     .set_flags(DB_DBT_PARTIAL);
     dbtData     .set_dlen(0);
//     dbtData     .set_size(0);
//     dbtData     .set_doff(0);
//     dbtData     .set_data(NULL);
     try
          iResult     =     m_pdbTic->get(NULL, &dbtKey, &dbtData, 0);
     catch(DbException &e)
          m_pdbRafCal->err(e.get_errno(), "Error!");
          sprintf(caError,     e.what());
     catch(std::exception &e)
          m_pdbRafCal->errx("Error! %s", e.what());
          sprintf(caError,     e.what());
     if(iResult != 0)
          return     FALSE;
     return     TRUE;
all times i got "Db::get: Invalid argument".
Thanks,
DelNeto

Answer 1

Thanks Alexander.Gorrod, the return value, from get, was "-858993460", but the error code at exception was "-30999", that is DB_BUFFER_SMALL. The final code look like this:
memset(&dbtData, 0, sizeof(dbtData));
dbtData.set_flags(DB_DBT_USERMEM);
dbtData.set_ulen(0);
try
// You can then call get as you would normally:
iResult = m_pdbTic->get(NULL, &dbtKey, &dbtData, 0);
catch(DbException &e)
if(e.get_errno() == DB_BUFFER_SMALL)
return TRUE;
catch(std::exception &e)
sprintf(caError,     e.what());
return FALSE;
Thanks for the tip,
DelNeto