MarshalOptions 屬性範例 (VC++)
這個範例會使用 MarshalOptions 屬性，指定哪些資料列會傳回伺服器 - 所有資料列或僅修改的資料列。
// BeginMarshalOptionsCpp.cpp
// compile with: /EHsc /c
#import "msado15.dll" no_namespace rename("EOF", "EndOfFile")
#include <stdio.h>
#include <ole2.h>
#include <conio.h>
#include <malloc.h>
#include "icrsint.h"
// This Class extracts only fname,lname from employees table
class CEmployeeRs : public CADORecordBinding {
BEGIN_ADO_BINDING(CEmployeeRs)
// Column fname is the 1st field in the recordset
ADO_VARIABLE_LENGTH_ENTRY2(1, adVarChar, m_szemp_fname, sizeof(m_szemp_fname), lemp_fnameStatus, TRUE)
// Column lname is the 2nd field in the recordset
ADO_VARIABLE_LENGTH_ENTRY2(2, adVarChar, m_szemp_lname, sizeof(m_szemp_lname), lemp_lnameStatus, TRUE)
END_ADO_BINDING()
public:
CHAR m_szemp_fname[21];
ULONG lemp_fnameStatus;
CHAR m_szemp_lname[31];
ULONG lemp_lnameStatus;
};
// Function declarations
inline void TESTHR(HRESULT x) { if FAILED(x) _com_issue_error(x); };
void MarshalOptionsX();
void PrintProviderError(_ConnectionPtr pConnection);
void PrintComError(_com_error &e);
int main() {
if (FAILED(::CoInitialize(NULL)))
return -1;
MarshalOptionsX();
::CoUninitialize();
}
void MarshalOptionsX() {
// Define string variables
char * token1;
_bstr_t strCnn("Provider='sqloledb'; Data Source='My_Data_Source'; Initial Catalog='pubs'; Integrated Security='SSPI';");
// Define ADO object pointers. Initialize pointers on define. These are in the ADODB:: namespace.
_RecordsetPtr pRstEmployees = NULL;
// Define Other Variables
IADORecordBinding *picRs = NULL; // Interface Pointer declared
CEmployeeRs emprs; // C++ Class Object
HRESULT hr = S_OK;
LPSTR strOldFirst = NULL;
LPSTR strOldLast = NULL;
try {
// Open recordset with names from Employee table.
TESTHR(pRstEmployees.CreateInstance(__uuidof(Recordset)));
pRstEmployees->CursorType = adOpenKeyset;
pRstEmployees->LockType = adLockOptimistic;
pRstEmployees->CursorLocation = adUseClient;
pRstEmployees->Open("SELECT fname, lname FROM Employee ORDER BY lname", strCnn,
adOpenKeyset, adLockOptimistic, adCmdText);
// Open an IADORecordBinding interface pointer which
// we'll use for Binding Recordset to a class.
TESTHR(pRstEmployees->QueryInterface( __uuidof(IADORecordBinding), (LPVOID*)&picRs) );
// Bind the Recordset to a C++ Class here.
TESTHR(picRs->BindToRecordset(&emprs));
// Store Original Data
strOldFirst = (LPSTR) malloc(sizeof(emprs.m_szemp_fname));
strOldLast = (LPSTR) malloc(sizeof(emprs.m_szemp_lname));
// Set the final character of the destination string to NULL.
strOldFirst[sizeof(emprs.m_szemp_fname)-1] = '\0';
// The source string will get truncated if its length is
// longer than the length of the destination string minus one.
strncpy_s(strOldFirst, sizeof(emprs.m_szemp_lname), strtok_s(emprs.m_szemp_fname, " ", &token1), sizeof(emprs.m_szemp_fname) - 1);
// Set the final character of the destination string to NULL.
strOldLast[sizeof(emprs.m_szemp_lname) - 1] = '\0';
// The source string will get truncated if its length is
// longer than the length of the destination string minus one.
strncpy_s(strOldLast, sizeof(emprs.m_szemp_lname), strtok_s(emprs.m_szemp_lname," ", &token1), sizeof(emprs.m_szemp_lname) - 1);
// Change Data in Edit Buffer. Set the final character of the destination string to NULL.
emprs.m_szemp_fname[sizeof(emprs.m_szemp_fname) - 1] = '\0';
// The source string will be truncated if its length is longer than the length of the destination string minus one.
strncpy_s(emprs.m_szemp_fname, _countof(emprs.m_szemp_fname), "Linda", sizeof(emprs.m_szemp_fname) -1);
// Set the final character of the destination string to NULL.
emprs.m_szemp_lname[sizeof(emprs.m_szemp_lname)-1] = '\0';
// The source string will be truncated if its length is longer than the destination string minus one.
strncpy_s(emprs.m_szemp_lname, _countof(emprs.m_szemp_lname), "Kobara", sizeof(emprs.m_szemp_lname) -1);
// Show contents of buffer and get user input
printf("Edit in Progress:\n");
printf("Original Data = %s %s \n",strOldFirst,strOldLast);
printf("Data in buffer = %s %s \n", emprs.lemp_fnameStatus == adFldOK ? emprs.m_szemp_fname : "<NULL>",
emprs.lemp_lnameStatus == adFldOK ? emprs.m_szemp_lname : "<NULL>");
printf("Use Update to replace the original data with the buffered data in the Recordset?\nEnter (y/n) :?");
char opt1 = _getch();
if (toupper(opt1)=='Y') {
printf("\nWould you like to send all the rows in the recordset back to the server?\nEnter (y/n):");
char opt2 = _getch();
if (toupper(opt2) == 'Y') {
pRstEmployees->MarshalOptions = adMarshalAll;
picRs->Update(&emprs);
}
}
else {
printf("\nWould you like to send only modified rows back to the server?\nEnter (y/n):");
char opt3 = _getch();
if (toupper(opt3) == 'Y') {
pRstEmployees->MarshalOptions = adMarshalModifiedOnly;
picRs->Update(&emprs);
}
}
// Show the resulting data
printf("\nData In the Recordset = %s %s\n",
emprs.lemp_fnameStatus == adFldOK ?
emprs.m_szemp_fname : "<NULL>",
emprs.lemp_lnameStatus == adFldOK ?
emprs.m_szemp_lname : "<NULL>");
// Restore original data because this is a demonstration
if ((strcmp(strOldFirst,emprs.m_szemp_fname)) && (strcmp(strOldLast, emprs.m_szemp_lname))) {
// Set the final character of the destination string to NULL.
emprs.m_szemp_fname[sizeof(emprs.m_szemp_fname)-1] = '\0';
// The source string will get truncated if its length is
// longer than the length of the destination string minus one.
strncpy_s(emprs.m_szemp_fname, _countof(emprs.m_szemp_fname), strOldFirst, sizeof(emprs.m_szemp_fname)-1);
// Set the final character of the destination string to NULL.
emprs.m_szemp_lname[sizeof(emprs.m_szemp_lname)-1] = '\0';
// The source string will get truncated if its length is
// longer than the length of the destination string minus one.
strncpy_s(emprs.m_szemp_lname, _countof(emprs.m_szemp_lname), strOldLast, sizeof(emprs.m_szemp_lname) -1);
picRs->Update(&emprs);
}
}
catch(_com_error &e) {
// Notify the user of errors if any.
// Pass a connection pointer accessed from the Recordset.
_variant_t vtConnect = pRstEmployees->GetActiveConnection();
// GetActiveConnection returns connect string if connection
// is not open, else returns Connection object.
switch(vtConnect.vt) {
case VT_BSTR:
PrintComError(e);
break;
case VT_DISPATCH:
PrintProviderError(vtConnect);
break;
default:
printf("Errors occurred.");
break;
}
}
// Clean up objects before exit.
// Deallocate memory
if (strOldFirst)
free(strOldFirst);
if (strOldLast)
free(strOldLast);
// Release the IADORecordset Interface here
if (picRs)
picRs->Release();
if (pRstEmployees)
if (pRstEmployees->State == adStateOpen)
pRstEmployees->Close();
}
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, (LPCSTR) pErr->Description);
}
}
}
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);
}