| ADO 2.5 Samples |  |
| ADO 2.5 Samples | |
This example uses the Move method to position the record pointer based on user input.
// BeginMoveCpp
#import "C:\Program Files\Common Files\System\ADO\msado15.dll" \
no_namespace rename("EOF", "EndOfFile")
#include <stdio.h>
#include <ole2.h>
#include <stdlib.h>
#include <conio.h>
#include "MoveX.h"
// Function Declaration.
inline void TESTHR(HRESULT x) {if FAILED(x) _com_issue_error(x);};
void MoveX(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;
MoveX();
::CoUninitialize();
}
//////////////////////////////////////////////////
// //
// MoveX Function //
// //
//////////////////////////////////////////////////
void MoveX(void)
{
// Define ADO object pointers.
// Initialize pointers on define.
// These are in the ADODB:: namespace.
_RecordsetPtr pRstAuthors = NULL;
// 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='MySqlServer';"
"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, Enter to quit): ");
mygets(strTemp, 5);
strMove = strtok(strTemp," \t");
if (strMove == NULL)
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 occured.");
break;
}
}
// Clean up objects before exit.
//Release the IADORecordset Interface here
if (picRs)
picRs->Release();
if (pRstAuthors)
if (pRstAuthors->State == adStateOpen)
pRstAuthors->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,
(LPCSTR) 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);
}
// EndMoveCpp
MoveX.h
// BeginMoveH
#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;
};
// EndMoveH