ActiveCommand-Eigenschaft – Beispiel (VC++)
In diesem Beispiel wird die ActiveCommand-Eigenschaft veranschaulicht.
An eine Unterroutine wird ein Recordset-Objekt übergeben, dessen ActiveCommand-Eigenschaft verwendet wird, um den Befehlstext und Parameter anzuzeigen, mit denen das Recordset erstellt wurde.
Beispiel
// BeginActiveCommandCpp.cpp
// compile with: /EHsc /c
#import "msado15.dll" no_namespace rename("EOF", "EndOfFile")
#include <ole2.h>
#include <stdio.h>
#include <conio.h>
#include "icrsint.h"
// 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;
};
// Function declarations
inline void TESTHR(HRESULT x) { if FAILED(x) _com_issue_error(x); };
void ActiveCommandX();
void ActiveCommandXprint(_RecordsetPtr pRst);
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;
}
int main() {
if (FAILED(::CoInitialize(NULL)))
return -1;
ActiveCommandX();
::CoUninitialize();
}
void ActiveCommandX() {
HRESULT hr = S_OK;
char * token1;
// Define ADO object pointers, initialize pointers on define. These are in the ADODB:: namespace.
_ConnectionPtr pConnection = NULL;
_CommandPtr pCmd = NULL;
_RecordsetPtr pRstAuthors = NULL;
// Definitions of other variables
_bstr_t strCnn("Provider='sqloledb'; Data Source='My_Data_Source'; Initial Catalog='pubs'; Integrated Security='SSPI';");
_bstr_t strPrompt;
_bstr_t strName;
CHAR strcharName[50];
try {
// Open connection.
TESTHR(pConnection.CreateInstance(__uuidof(Connection)));
TESTHR(pRstAuthors.CreateInstance(__uuidof(Recordset)));
TESTHR(pCmd.CreateInstance(__uuidof(Command)));
printf ("ActiveCommandX Example\n\n");
strPrompt = "Enter an author's name (e.g., Ringer): ";
printf(strPrompt);
mygets(strcharName, 50);
char *tempStr = strtok_s(strcharName, " \t", &token1);
strName = tempStr;
pCmd->CommandText = "SELECT * FROM authors WHERE au_lname = ?";
pCmd->Parameters->Append(pCmd->CreateParameter("LastName", adChar, adParamInput, 20, strName));
pConnection->Open (strCnn, "", "", adConnectUnspecified);
pCmd->PutActiveConnection(_variant_t((IDispatch*)pConnection));
pRstAuthors = pCmd->Execute(NULL, NULL, adCmdText);
ActiveCommandXprint(pRstAuthors);
} // End Try statement.
catch(_com_error &e) {
// Notify the user of errors if any.
// Pass a connection pointer accessed from the Recordset.
PrintProviderError(pConnection);
PrintComError(e);
}
// Clean up objects before exit.
if (pRstAuthors)
if (pRstAuthors->State == adStateOpen)
pRstAuthors->Close();
if (pConnection)
if (pConnection->State == adStateOpen)
pConnection->Close();
}
void ActiveCommandXprint(_RecordsetPtr pRst = NULL) {
// Varible Declaraion & initialization
IADORecordBinding *picRs = NULL; // Interface Pointer declared.
CAuthorsRs autrs; // C++ class object
_bstr_t strName;
// Open an IADORecordBinding interface pointer which
// we'll use for Binding Recordset to a class
TESTHR(pRst->QueryInterface(__uuidof(IADORecordBinding),(LPVOID*)&picRs));
// Bind the Recordset to a C++ Class here
TESTHR(picRs->BindToRecordset(&autrs));
strName = ((_CommandPtr)pRst->GetActiveCommand())->GetParameters()->GetItem("LastName")->Value;
printf("Command text = '%s'\n", (LPCSTR)((_CommandPtr)pRst->GetActiveCommand())->CommandText);
printf("Parameter = '%s'\n", (LPCSTR)strName);
if (pRst->BOF)
printf("Name = '%s'not found.", (LPCSTR)strName);
else {
printf ("Name = '%s %s'",
autrs.lau_fnameStatus == adFldOK ? autrs.m_szau_fname : "<NULL>",
autrs.lau_lnameStatus == adFldOK ? autrs.m_szau_lname : "<NULL>");
}
// Release IADORecordset Interface
if (picRs)
picRs->Release();
}
void PrintProviderError(_ConnectionPtr pConnection) {
// Print Provider Errors from Connection object.
// pErr is a record object in the Connection's Error collection.
ErrorPtr pErr = NULL;
long nCount = 0;
long i = 0;
if ( (pConnection->Errors->Count) > 0) {
nCount = pConnection->Errors->Count;
// Collection ranges from 0 to (nCount - 1)
for ( i = 0 ; i < nCount ; i++ ) {
pErr = pConnection->Errors->GetItem(i);
printf("\t Error number: %x\t%s\n", 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);
}
Beispieleingabe
Ringer
Beispielausgabe
Command text = 'SELECT * FROM authors WHERE au_lname = ?'
Parameter = 'Ringer'
Name = 'Anne Ringer'