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Databases in Visual C++
- Thread starter darioars
- Start date
This is a broad question. There are many ways of connecting to a database in visual c++: DAO, ADO, ODBC
Which one you use depends on your requirements and the type of database you are using. Here are some good tutorials using MFC with databases:
Which one you use depends on your requirements and the type of database you are using. Here are some good tutorials using MFC with databases:
Cagliostro
Programmer
Code:
//using DAO
#import "G:\Program Files\Common Files\Microsoft Shared\DAO\dao360.dll"
#include "Debug\dao360.tlh"
#include<atlbase.h>
#include<iostream>
using namespace std;
int main()
{
CoInitialize(0);
{
HRESULT hr = -1;
CComPtr<IUnknown> app;
DAO::_DBEngine* eng;
DAO::Workspace* wr;
DAO::Database* db;
DAO::Recordset* rs;
VARIANT_BOOL eof;
VARIANT_BOOL bof;
DAO::Fields* fs;
DAO::_Field* f1;
DAO::_Field* f2;
hr = app.CoCreateInstance(L"DAO.DBEngine.36");
hr = app->QueryInterface(&eng);
hr = eng->raw_CreateWorkspace(L"TestWorkSpace1", L"Admin", L"", _variant_t(DAO::dbUseJet), &wr);
//open dbname, ifexclusive, ifreadonly, connect, retdb
hr = wr->raw_OpenDatabase(_bstr_t(L"c:\\db1.mdb"), _variant_t(0), _variant_t(0), _variant_t(L""), &db);
hr = db->raw_OpenRecordset(_bstr_t(L"select * from Table1"),
_variant_t(DAO::dbOpenDynaset), _variant_t(0), _variant_t(2), &rs);
hr = rs->get_Fields(&fs);
hr = fs->get_Item(_variant_t(0), &f1);
hr = fs->get_Item(_variant_t(1), &f2);
wcout<< L"<"<< (BSTR)f1->Name<< L"><" << f2->Name<< L">"<< endl;
VARIANT valx, valy;
while(true)
{
hr = rs->get_EOF(&eof);
hr = rs->get_BOF(&bof);
if(eof)break;
if(bof)break;
f1->get_Value(&valx);
f2->get_Value(&valy);
wcout<< L"{"<< (wchar_t*)_bstr_t(_variant_t(valx))<< L"}{";
wcout<< (wchar_t*)_bstr_t(_variant_t(valy))<< L"}"<< endl;
hr = rs->MoveNext();
}
hr = hr;
}
CoUninitialize();
return 0;
}
// using DAO
#import "G:\Program Files\Common Files\System\ADO\msado15.dll"
#include "Debug\msado15.tlh"
#include<atlbase.h>
#include<iostream>
using namespace std;
int main()
{
CoInitialize(0);
{
HRESULT hr = -1;
CComPtr<IUnknown> cnnobj;
CComPtr<IUnknown> rdsnobj;
CComPtr<IUnknown> errobj;
hr = cnnobj.CoCreateInstance(L"ADODB.Connection.2.7");
ADODB::_Connection* cnn;
ADODB::_Recordset* rds;
ADODB::Error* err;
BSTR berr;
ADODB::Fields* fds;
ADODB::Field* fd1;
ADODB::Field* fd2;
hr = cnnobj->QueryInterface(&cnn);
hr = cnn->Open(L"driver={Microsoft Access Driver (*.mdb)};dbq=[c:\\db1.mdb];", L"", L"", -1);
hr = rdsnobj.CoCreateInstance(L"ADODB.Recordset.2.7");
hr = rdsnobj->QueryInterface(&rds);
hr = errobj.CoCreateInstance(L"ADODB.Error.2.7");
hr = errobj->QueryInterface(&err);
hr = rds->put_ActiveConnection(_variant_t(cnn));
hr = rds->Open(_variant_t("select * from Table1"), _variant_t(cnn), ADODB::adOpenUnspecified, ADODB::adLockUnspecified, -1);
VARIANT_BOOL eof;
VARIANT_BOOL bof;
hr = rds->MoveFirst();
hr = rds->get_Fields(&fds);
hr = fds->get_Item(_variant_t(L"X"), &fd1);
hr = fds->get_Item(_variant_t(L"Y"), &fd2);
BSTR namex;
BSTR namey;
hr = fd1->get_Name(&namex);
hr = fd2->get_Name(&namey);
cout<< "filends count: "<< fds->GetCount()<< endl;
wcout<< L"<"<< namex<< L"><"<< namey<< L">"<< endl;
VARIANT valx, valy;
while(true)
{
hr = rds->get_EOF(&eof);
hr = rds->get_BOF(&bof);
if(eof)break;
if(bof)break;
fd1->get_Value(&valx);
fd2->get_Value(&valy);
wcout<< L"{"<< (wchar_t*)_bstr_t(_variant_t(valx))<< L"}{";
wcout<< (wchar_t*)_bstr_t(_variant_t(valy))<< L"}"<< endl;
hr = rds->MoveNext();
}
hr = rds->Close();
hr = cnn->Close();
}
CoUninitialize();
return 0;
}
//using ODBC
#include<windows.h>
#include<iostream>
#include<string>
#include<sql.h>
#include<sqlext.h>
using namespace std;
int main()
{
HENV hEnv;
HDBC hDbc;
RETCODE rc;
int iOut;
char strOut[256];
char szDSN[256] = "driver={Microsoft Access Driver (*.mdb)};dbq=[c:\\db1.mdb];";
//dsn samples:
//"driver={Microsoft Access Driver (*.mdb)};dbq=[f:\\db1.mdb];"
//"driver={SQL Server};pwd={password there};Server={server name};Database={dbname there}"
//driver names for different databases:
//{SQL Server}
//{Microsoft ODBC for Oracle}
//{Oracle in oracle9}
//{Microsoft Access Driver (*.mdb)}
//{MySQL ODBC 3.51 Driver}
char* szSql = "select * from table1";
rc = SQLAllocEnv(&hEnv);
rc = SQLAllocConnect(hEnv, &hDbc);
rc = SQLDriverConnect(hDbc, NULL, (unsigned char*)szDSN,
SQL_NTS, (unsigned char*)strOut,
255, (SQLSMALLINT*)&iOut, SQL_DRIVER_NOPROMPT);
{
int ival;
char chval[128];
int ret1;
int ret2;
HSTMT hStmt;
rc = SQLAllocStmt(hDbc,&hStmt);
rc = SQLPrepare(hStmt,(unsigned char*)szSql, SQL_NTS);//1
//rc = SQLBindCol(hStmt, tab_column, tr_type, tr_value, tr_len, len_or_ind);
rc = SQLBindCol(hStmt, 1, SQL_C_ULONG, &ival, 4, (SQLINTEGER*)& ret1);
rc = SQLBindCol(hStmt, 2, SQL_C_CHAR, chval, 128, (SQLINTEGER*)&ret2);
rc = SQLExecute(hStmt); //2
//if you have queries like drop/create/many update...
//instead of //1 //2 and //3 you could use
//rc=SQLExecDirectA(hStmt,(unsigned char*)szSql,SQL_NTS);
cout<< ">table:"<< endl;
while(1) //3
{
rc = SQLFetch(hStmt);
if(rc != SQL_SUCCESS && rc != SQL_SUCCESS_WITH_INFO)break;
cout<< "{"<< ival<<"}{"<< chval<< "}"<< endl;
}
rc=SQLFreeStmt(hStmt, SQL_DROP);
}
rc = SQLDisconnect(hDbc);
rc = SQLFreeEnv(hEnv);
return 0;
}Ion Filipski
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