Refresh Method Example (VC++)
This example demonstrates using the Refresh method to refresh the Parameters collection for a stored procedure Command object.
// BeginRefreshCpp
#import "msado15.dll" \
no_namespace rename("EOF", "EndOfFile")
#include <ole2.h>
#include <stdio.h>
#include <conio.h>
#include "RefreshX.h"
// Function declarations
inline void TESTHR(HRESULT x) {if FAILED(x) _com_issue_error(x);};
void RefreshX(void);
void PrintProviderError(_ConnectionPtr pConnection);
void PrintComError(_com_error &e);
inline char* mygets(char* strDest, int n)
{
char strExBuff[10];
char* pstrRet = fgets(strDest, n, stdin);
if (pstrRet == NULL)
return NULL;
if (!strrchr(strDest, '\n'))
// Exhaust the input buffer.
do
{
fgets(strExBuff, sizeof(strExBuff), stdin);
}while (!strrchr(strExBuff, '\n'));
else
// Replace '\n' with '\0'
strDest[strrchr(strDest, '\n') - strDest] = '\0';
return pstrRet;
}
//////////////////////////////
// //
// Main Function //
// //
//////////////////////////////
void main()
{
if(FAILED(::CoInitialize(NULL)))
return;
RefreshX();
::CoUninitialize();
}
////////////////////////////////////////////
// //
// RefreshX Function //
// //
////////////////////////////////////////////
void RefreshX(void)
{
HRESULT hr = S_OK;
// Define string variables.
_bstr_t strCnn("Provider='sqloledb';Data Source='MySqlServer';"
"Initial Catalog='pubs';Integrated Security='SSPI';");
// Define ADO object pointers.
// Initialize pointers on define.
// These are in the ADODB:: namespace.
_ConnectionPtr pConnection = NULL;
_CommandPtr pCmdByRoyalty = NULL;
_RecordsetPtr pRstByRoyalty = NULL;
_RecordsetPtr pRstAuthors = NULL;
IADORecordBinding *picRs = NULL; //Interface Pointer declared.
CAuthorsRs authorsrs; //C++ class object
try
{
// Open connection.
TESTHR(pConnection.CreateInstance(__uuidof(Connection)));
pConnection->Open (strCnn, "", "", adConnectUnspecified);
// Open a command object for a stored procedure,
// with one parameter.
TESTHR(pCmdByRoyalty.CreateInstance(__uuidof(Command)));
pCmdByRoyalty->ActiveConnection = pConnection;
pCmdByRoyalty->CommandText = "byroyalty";
pCmdByRoyalty->CommandType = adCmdStoredProc;
pCmdByRoyalty->Parameters->Refresh();
// Get parameter value and execute the command,
// storing the results in a recordset.
char *strRoyalty;
char strTemp[5];
do
{
printf("\n\nEnter royalty : ");
mygets(strTemp, 5);
strRoyalty = strtok(strTemp," \t");
if(strRoyalty == NULL)
{
exit(1);
}
// if the input is not numeric then notify the user.
if(!atoi(strRoyalty))
{
printf("\nExpecting numeric value...");
continue;
}
}while(!atoi(strRoyalty));
_variant_t vtroyal;
vtroyal.vt = VT_I2;
vtroyal.iVal = atoi(strRoyalty);
_variant_t Index;
Index.vt = VT_I2;
Index.iVal = 1;
pCmdByRoyalty->GetParameters()->GetItem(Index)->
PutValue(vtroyal);
pRstByRoyalty = pCmdByRoyalty->
Execute(NULL,NULL,adCmdStoredProc);
// Open the Authors table to get author names for display.
TESTHR(pRstAuthors.CreateInstance(__uuidof(Recordset)));
pRstAuthors->Open ("authors",
_variant_t((IDispatch *) pConnection, true),
adOpenForwardOnly, adLockReadOnly, adCmdTable);
//Open an IADORecordBinding interface pointer which we'll use for
//Binding Recordset to a class.
TESTHR(pRstAuthors->QueryInterface(
__uuidof(IADORecordBinding),(LPVOID*)&picRs));
//Bind the Recordset to a C++ Class here.
TESTHR(picRs->BindToRecordset(&authorsrs));
// Print current data in the recordset,adding
// author names from Authors table.
printf("\n\nAuthors with %s percent royalty\n\n",strRoyalty);
while(!(pRstByRoyalty->EndOfFile))
{
_bstr_t strAuthorID = pRstByRoyalty->Fields->GetItem(
"au_id")->Value;
printf(" %s",(LPCSTR) (_bstr_t) pRstByRoyalty->Fields->
GetItem("au_id")->Value);
pRstAuthors->Filter = "au_id ='"+strAuthorID+"'";
printf(", %s %s\n\n",authorsrs.lau_fnameStatus == adFldOK ?
authorsrs.m_szau_fname : "<NULL>",
authorsrs.lau_lnameStatus == adFldOK ?
authorsrs.m_szau_lname : "<NULL>");
pRstByRoyalty->MoveNext();
}
}
catch (_com_error &e)
{
PrintProviderError(pConnection);
PrintComError(e);
}
if (pRstByRoyalty)
if (pRstByRoyalty->State == adStateOpen)
pRstByRoyalty->Close();
if (pRstAuthors)
if (pRstAuthors->State == adStateOpen)
pRstAuthors->Close();
if (pConnection)
if (pConnection->State == adStateOpen)
pConnection->Close();
}
///////////////////////////////////////////////////////////
// //
// PrintProviderError Function //
// //
///////////////////////////////////////////////////////////
void PrintProviderError(_ConnectionPtr pConnection)
{
// Print Provider Errors from Connection object.
// pErr is a record object in the Connection's Error collection.
ErrorPtr pErr = NULL;
if( (pConnection->Errors->Count) > 0)
{
long nCount = pConnection->Errors->Count;
// Collection ranges from 0 to nCount -1.
for(long i = 0;i < nCount;i++)
{
pErr = pConnection->Errors->GetItem(i);
printf("\t Error number: %x\t%s", pErr->Number,
pErr->Description);
}
}
}
///////////////////////////////////////////////////////////
// //
// PrintComError Function //
// //
///////////////////////////////////////////////////////////
void PrintComError(_com_error &e)
{
_bstr_t bstrSource(e.Source());
_bstr_t bstrDescription(e.Description());
// Print COM errors.
printf("Error\n");
printf("\tCode = %08lx\n", e.Error());
printf("\tCode meaning = %s\n", e.ErrorMessage());
printf("\tSource = %s\n", (LPCSTR) bstrSource);
printf("\tDescription = %s\n", (LPCSTR) bstrDescription);
}
// EndRefreshCpp
RefreshX.h
// BeginRefreshH
#include "icrsint.h"
//This Class extracts lname,fname from authors table.
class CAuthorsRs : public CADORecordBinding
{
BEGIN_ADO_BINDING(CAuthorsRs)
// Column lname is the 2nd field in the recordset
ADO_VARIABLE_LENGTH_ENTRY2(2, adVarChar, m_szau_lname,
sizeof(m_szau_lname), lau_lnameStatus, TRUE)
// Column fname is the 3rd field in the recordset.
ADO_VARIABLE_LENGTH_ENTRY2(3, adVarChar, m_szau_fname,
sizeof(m_szau_fname), lau_fnameStatus, TRUE)
END_ADO_BINDING()
public:
CHAR m_szau_fname[21];
ULONG lau_fnameStatus;
CHAR m_szau_lname[41];
ULONG lau_lnameStatus;
};
// EndRefreshH