CursorType、LockType 和 EditMode 属性示例 (VC++)
此示例演示如何在打开 Recordset 之前设置 CursorType 和 LockType 属性。 它还显示了各种条件下 EditMode 属性的值。 运行此过程需要 EditModeOutput 函数。
示例
// CursorType_LockType_EditMode_Property_Example.cpp
// compile with: /EHsc
#import "msado15.dll" no_namespace rename("EOF", "EndOfFile")
#include <ole2.h>
#include <stdio.h>
#include <conio.h>
// Function declaration
inline void TESTHR(HRESULT x) { if FAILED(x) _com_issue_error(x); };
void EditModeX();
void EditModeOutput(char *, int);
void PrintProviderError(_ConnectionPtr pConnection);
void PrintComError(_com_error &e);
int main() {
if ( FAILED(::CoInitialize(NULL)) )
return -1;
EditModeX();
::CoUninitialize();
}
void EditModeX() {
// Define ADO object pointers. Initialize pointers on define.
// These are in the ADODB:: namespace.
_RecordsetPtr pRstEmployees = NULL;
_ConnectionPtr pConnection = NULL;
HRESULT hr = S_OK;
_bstr_t strCnn("Provider='sqloledb'; Data Source='My_Data_Source'; Initial Catalog='pubs'; Integrated Security='SSPI';");
try {
// Open a connection
TESTHR(pConnection.CreateInstance(__uuidof(Connection)));
hr = pConnection->Open(strCnn, "", "", adConnectUnspecified);
// Open recordset with data from employee table
TESTHR(pRstEmployees.CreateInstance(__uuidof(Recordset)));
pRstEmployees->CursorLocation = adUseClient;
pRstEmployees->CursorType = adOpenStatic;
pRstEmployees->LockType = adLockBatchOptimistic;
pRstEmployees->Open("employee", _variant_t((IDispatch *) pConnection,true),
adOpenStatic, adLockBatchOptimistic, adCmdTable);
// Show the EditMode property under different editing states.
pRstEmployees->AddNew ();
pRstEmployees->Fields->Item["emp_id"]->Value = (_bstr_t)("T-T55555M");
pRstEmployees->Fields->Item["fname"]->Value = (_bstr_t)("temp_fname");
pRstEmployees->Fields->Item["lname"]->Value = (_bstr_t)("temp_lname");
EditModeOutput("After AddNew: ", pRstEmployees->EditMode);
pRstEmployees->UpdateBatch(adAffectCurrent);
EditModeOutput("After Update: ", pRstEmployees->EditMode);
pRstEmployees->Fields->Item["fname"]->Value = (_bstr_t)("test");
EditModeOutput("After Edit: ", pRstEmployees->EditMode);
// Delete new record because this is a demonstration.
pConnection->Execute("DELETE FROM employee WHERE emp_id = 'T-T55555M'",
NULL, adCmdText);
}
catch(_com_error &e) {
// Display errors, if any. Pass connection pointer accessed from the Recordset.
PrintProviderError(pConnection);
PrintComError(e);
}
// Clean up objects before exit.
if (pRstEmployees)
if (pRstEmployees->State == adStateOpen)
pRstEmployees->Close();
if (pConnection)
if (pConnection->State == adStateOpen)
pConnection->Close();
}
void EditModeOutput(char *strTemp, int intEditMode) {
// Print report based on the value of the EditMode property.
printf("\n%s", strTemp);
printf("\n EditMode = ");
switch (intEditMode) {
case adEditNone :
printf("adEditNone");
break;
case adEditInProgress :
printf("adEditInProgress");
break;
case adEditAdd :
printf("adEditAdd");
break;
}
}
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("\n\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);
}
After AddNew:
EditMode = adEditAdd
After Update:
EditMode = adEditNone
After Edit:
EditMode = adEditInProgress
另请参阅
CursorType 属性 (ADO)
EditMode 属性
LockType 属性 (ADO)
记录集对象 (ADO)
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