Re: code example for PQgetCopyData

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From: pgsql-general-owner(at)postgresql(dot)org
[mailto:pgsql-general-owner(at)postgresql(dot)org] On Behalf Of Dave Huber
Sent: Thursday, December 03, 2009 9:18 AM
To: pgsql-general(at)postgresql(dot)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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