Move Method Example (VC++)
This example uses the Move method to position the record pointer based on user input.
Example
// BeginMoveCpp.cpp
// compile with: /EHsc /c
#import "msado15.dll" no_namespace rename("EOF", "EndOfFile")
#include <stdio.h>
#include <ole2.h>
#include <stdlib.h>
#include <conio.h>
#include "icrsint.h"
// This Class extracts fname, lname, city and state from the "authors" table.
class CAuthorsRs : public CADORecordBinding {
BEGIN_ADO_BINDING(CAuthorsRs)
// Column au_id is the 1st field in the recordset
ADO_VARIABLE_LENGTH_ENTRY2(2, adVarChar, m_au_fname, sizeof(m_au_fname), lemp_fnameStatus, TRUE)
ADO_VARIABLE_LENGTH_ENTRY2(3, adVarChar, m_au_lname, sizeof(m_au_lname), lemp_lnameStatus, TRUE)
ADO_VARIABLE_LENGTH_ENTRY2(4, adVarChar, m_au_city, sizeof(m_au_city), lemp_cityStatus, TRUE)
ADO_VARIABLE_LENGTH_ENTRY2(5, adChar, m_au_state, sizeof(m_au_state), lemp_stateStatus, TRUE)
END_ADO_BINDING()
public:
char m_au_fname[21];
ULONG lemp_fnameStatus;
char m_au_lname[41];
ULONG lemp_lnameStatus;
char m_au_city[21];
ULONG lemp_cityStatus;
char m_au_state[3];
ULONG lemp_stateStatus;
};
// Function Declaration.
inline void TESTHR(HRESULT x) { if FAILED(x) _com_issue_error(x); };
void MoveX();
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;
MoveX();
::CoUninitialize();
}
void MoveX() {
// Define ADO object pointers. Initialize pointers on define. These are in the ADODB:: namespace.
_RecordsetPtr pRstAuthors = NULL;
char *token1;
// Define Other Variables
IADORecordBinding *picRs = NULL; // Interface Pointer declared
CAuthorsRs authorsrs; // C++ class object
HRESULT hr = S_OK;
// Open Authors table
_bstr_t strCnn("Provider='sqloledb'; Data Source='My_Data_Source'; Initial Catalog='pubs'; Integrated Security='SSPI';");
try {
// Open recordset from Authors table.
TESTHR(pRstAuthors.CreateInstance(__uuidof(Recordset)));
pRstAuthors->CursorType = adOpenStatic;
// Use client cursor to allow use of AbsolutePosition property.
pRstAuthors->CursorLocation = adUseClient;
pRstAuthors->Open("SELECT au_id, au_fname, au_lname, city, "
"state FROM Authors ORDER BY au_lname", strCnn, adOpenStatic, adLockReadOnly, adCmdText);
// 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));
pRstAuthors->MoveFirst();
char * strMove;
char strTemp[5];
while (true) {
// Display information about current record and ask how many records to move.
printf("Record %ld of %d\n", pRstAuthors->AbsolutePosition, pRstAuthors->RecordCount);
printf("Author: %s %s\n",
authorsrs.lemp_fnameStatus == adFldOK ?
authorsrs.m_au_fname : "<NULL>",
authorsrs.lemp_lnameStatus == adFldOK ?
authorsrs.m_au_lname : "<NULL>");
printf("Location: %s, %s\n\n",
authorsrs.lemp_cityStatus == adFldOK ?
authorsrs.m_au_city : "<NULL>",
authorsrs.lemp_stateStatus == adFldOK ?
authorsrs.m_au_state : "<NULL>");
printf("Enter number of records to Move \n(positive or negative, 0 (zero) to quit): ");
mygets(strTemp, 5);
strMove = strtok_s(strTemp, "\t", &token1);
if (strMove == NULL || *strMove == '0')
break;
// if the input is not numeric then notify the user.
if (!atol(strMove)) {
printf("Expecting numeric value...\n");
continue;
}
// Store bookmark in case the Move goes too far forward or backward.
_variant_t varBookmark = pRstAuthors->Bookmark;
// Move method requires parameter of data type Long.
long lngMove = atol(strMove);
pRstAuthors->Move(lngMove);
// Trap for BOF or EOF.
if (pRstAuthors->BOF) {
printf("Too far backward! Returning to current record.\n");
pRstAuthors->Bookmark = varBookmark;
}
if (pRstAuthors->EndOfFile) {
printf("Too far forward! Returning to current record.\n");
pRstAuthors->Bookmark = varBookmark;
}
}
}
catch(_com_error &e) {
// Notify the user of errors if any.
// Pass a connection pointer accessed from the Recordset.
_variant_t vtConnect = pRstAuthors->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. Release the IADORecordset Interface here
if (picRs)
picRs->Release();
if (pRstAuthors)
if (pRstAuthors->State == adStateOpen)
pRstAuthors->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);
}
Sample Input
1
0
Sample Output
Record 1 of 23
Author: Abraham Bennet
Location: Berkeley, CA
Enter number of records to Move
(positive or negative, Enter to quit): Record 2 of 23
Author: Reginald Blotchet-Halls
Location: Corvallis, OR
Enter number of records to Move
(positive or negative, Enter to quit):