Try to get blob data from Oracle by OCI routines but get error: ORA-01008: not all variables bound - c++

Question

I try to get blob data from Oracle by OCI routines.
I use the next code but the exceute statement gives ther error: ORA-01008: not all variables bound
What do I wrong? Can anybody help me?
Thanks,
Kees Braaksma
void get_blob_data()
{
// The query
// The results of this methode
// if errstring is empty, the blob data can be found in the 4th parameter.
// otherwise the error is given in errstring
CString csQuery;
csQuery.Format("BEGIN get_blob('%s','%ld',:ERRSTRING,:BLOB); END;", "20", 200);
//init
OCIHandleAlloc((dvoid *)m_OCIEnvironment , (dvoid **)(&m_OCIStatement),
(ub4)OCI_HTYPE_STMT, (size_t)0, (dvoid **)0);
//Prepare statement voor query
OCIStmtPrepare(m_OCIStatement, m_OCIError, (text *)(csQuery),
(ub4)(strlen(csQuery)), (ub4)OCI_NTV_SYNTAX, (ub4)OCI_DEFAULT);
// output variables
char *pszResult = (char*)malloc(256);
memset(pszResult, 0, sizeof(pszResult));
Blob *blob = new Blob();
m_pIndicator1 = malloc(sizeof(OCIInd));
m_pDefine1 = NULL;
OCIDefineByPos(m_OCIStatement, &m_pDefine1, m_OCIError, (ub4)1,
(dvoid*)*pszResult,
(sb4)256, SQLT_STR,
(dvoid*)m_pIndicator1,
(ub2*)0, (ub2*)0, (ub4)OCI_DEFAULT);
m_pIndicator2 = malloc(sizeof(OCIInd));
m_pDefine2 = NULL;
OCIDescriptorAlloc(m_OCIEnvironment, &blob, (ub4)OCI_DTYPE_LOB, (size_t)0, (dvoid **)0);
OCIDefineByPos(m_OCIStatement, &m_pDefine2,
m_OCIError, (ub4)2,
(dvoid*)blob,
(sb4)-1, SQLT_BLOB,
(dvoid*)m_pIndicator2,
(ub2*)0, (ub2*)0, (ub4)OCI_DEFAULT));
iStatus = OCIStmtExecute(m_OCISrvCtx, m_OCIStatement, m_OCIError, (ub4)1, (ub4)0,
(OCISnapshot *)NULL, (OCISnapshot *)NULL,
(ub4)OCI_DEFAULT);
// results:
// iStatus = -1;
// Errorstring: ORA-01008: not all variables bound
}

Answer 1

You don't have any OCIBindByName() calls. OCIDefineByPos() is used when running SQL queries, which you aren't.
It's odd that you use a mixture of %s and bind variables in the PL/SQL call. I think you want to use bind variables for all parameters.
One handy hint is to see how ODPI-C uses OCI. For LOBs you can get either locators or data directly. The latter is a lot faster, but limited to 1G. It's arguably easiest to install Python and cx_Oracle, and run some samples e.g. ReturnLobsAsStrings.py. You can trace the OCI calls in dpiOci.c.
There are some sample OCI programs (sadly not so accessible - your DBA may be able to install them), look out for cdemolb.c and cdemolbs.c

Answer 2

Best Oracle-users,
Still have problems with getting a blob from Oracle. I use it so less.
Most of the time I copy some code and a new query is working fine.
I asked my collegue to change the function.
New the query is:
select ngm_transactie_pck.get_checkout_blob('20','200') from dual
the result of this function is a blob.
So i programmed:
static OCILobLocator *blob = NULL;
after OCIHandleAlloc() and OCIStmtPrepare() as in previous example i have:
OCIDescriptorAlloc(m_OCIEnvironment, &blob, (ub4)OCI_DTYPE_LOB, (size_t)0, (dvoid **)0);
CIDefineByPos(m_OCIStatement, &m_pDefine2,
m_OCIError, (ub4)1,
(dvoid*)&blob,
(sb4)-1, OCI_DTYPE_LOB,
(dvoid*)m_pIndicator2,
(ub2*)0, (ub2*)0, (ub4)OCI_DEFAULT));
The call to OciDefineByPos() gives crash/stackoverflow.
What do I wrong?
Greetz,
Kees