Re: code example for PQgetCopyData - Mailing list pgsql-general

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From: pgsql-general-owner@postgresql.org [mailto:pgsql-general-owner@postgresql.org] On Behalf Of Dave Huber
Sent: Thursday, December 03, 2009 9:18 AM
To: pgsql-general@postgresql.org
Subject: [GENERAL] code example for PQgetCopyData

Does anybody have a snippet where they use PQgetCopyData? I must be calling it wrong as it keep crashing my program. I’ve attached my code below. I am writing this for a Code Interface Node in LabVIEW.

 

Thanks,

Dave

 

MgErr CINRun(LStrHandle conninfo, LStrHandle copystr, TD1Hdl resultValues) {

      MgErr err = noErr;

      PGconn *pConn;

      PGresult* pResult = NULL;

      char* szCopyStr = NULL;

      char* errormsg = NULL;

      char** buffer = NULL;               // for retrieving the data

      int nLen;                                 // length of returned data

     

      // connect to the database

      char* szConnInfo = new char[LHStrLen(conninfo)+1];

      LToCStr((*(conninfo)), (CStr)szConnInfo);

      pConn = PQconnectdb(szConnInfo);

      delete [] szConnInfo;

 

      // check for errors connecting to database

      if (PQstatus(pConn) != CONNECTION_OK)

      {

            DbgPrintf("Connection to database failed: %s", PQerrorMessage(pConn));

      }

      else

      {

            // start the copy command

            szCopyStr = new char[LHStrLen(copystr)+1];

            LToCStr((*(copystr)), (CStr)szCopyStr);

 

            pResult = PQexec(pConn, szCopyStr);

            delete [] szCopyStr;

     

            // get the data

            int i = 0;

            while (nLen = PQgetCopyData(pConn, buffer, false) > 0)

            {

     

                  if (err = SetCINArraySize((UHandle)resultValues, 2, ++i))

                        goto out;

                  if (err = NumericArrayResize(uB, 1L, (UHandle*)(&(*resultValues)->elt[i-1]), nLen-1))

                        goto out;

                  LStrLen(*(*resultValues)->elt[i-1]) = nLen-1;                                 // set the Labview String size

                  MoveBlock(*buffer, LStrBuf(*(*resultValues)->elt[i-1]), nLen-1);  // copy the data to a new string

 

                  PQfreemem(*buffer);                                                                             // free the memory from getCopy

           

            }

            (*resultValues)->dimSize = i;

     

out:       

            PQclear(pResult);

 

            // see if there were errors

            if (nLen == -2)

            {

                  DbgPrintf("Copy Out failed: %s", PQerrorMessage(pConn));

            }

 

      }

      // close the connection

      PQfinish(pConn);

 

      return err;

}

 

Where is it blowing up?

 

 

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