VC++ 访问数据库实例详解图解

一 ADO 方式访问 Access

新建一个对话框工程，添加控件，如图；



创建Access数据库如图；



应用程序启动时进行COM初始化；

BOOL CDemoApp::InitInstance()

{
if (!SUCCEEDED(CoInitialize(NULL)))
{
::AfxMessageBox(_T("Failed to initialize COM!"));
return FALSE;
}

AfxEnableControlContainer();

对话框类实现文件代码如下；

// DemoDlg.cpp : implementation file

// Download by http://www.NewXing.com
#include "stdafx.h"

#include "Demo.h"

#include "DemoDlg.h"

#ifdef _DEBUG

#define new DEBUG_NEW

#undef THIS_FILE

static char THIS_FILE[] = __FILE__;

#endif

/////////////////////////////////////////////////////////////////////////////

// CAboutDlg dialog used for App About

class CAboutDlg : public CDialog

{

public:
CAboutDlg();

// Dialog Data
//{{AFX_DATA(CAboutDlg)
enum { IDD = IDD_ABOUTBOX };
//}}AFX_DATA

// ClassWizard generated virtual function overrides
//{{AFX_VIRTUAL(CAboutDlg)
protected:
virtual void DoDataExchange(CDataExchange* pDX);    // DDX/DDV support
//}}AFX_VIRTUAL

// Implementation

protected:
//{{AFX_MSG(CAboutDlg)
//}}AFX_MSG
DECLARE_MESSAGE_MAP()

};

CAboutDlg::CAboutDlg() : CDialog(CAboutDlg::IDD)

{
//{{AFX_DATA_INIT(CAboutDlg)
//}}AFX_DATA_INIT

}

void CAboutDlg::DoDataExchange(CDataExchange* pDX)

{
CDialog::DoDataExchange(pDX);
//{{AFX_DATA_MAP(CAboutDlg)
//}}AFX_DATA_MAP

}

BEGIN_MESSAGE_MAP(CAboutDlg, CDialog)
//{{AFX_MSG_MAP(CAboutDlg)
// No message handlers
//}}AFX_MSG_MAP

END_MESSAGE_MAP()

/////////////////////////////////////////////////////////////////////////////

// CDemoDlg dialog

CDemoDlg::CDemoDlg(CWnd* pParent /*=NULL*/)
: CDialog(CDemoDlg::IDD, pParent)

{
//{{AFX_DATA_INIT(CDemoDlg)
//}}AFX_DATA_INIT
// Note that LoadIcon does not require a subsequent DestroyIcon in Win32
m_hIcon = AfxGetApp()->LoadIcon(IDR_MAINFRAME);

if (!SUCCEEDED(m_pConnection.CreateInstance(__uuidof(Connection))))
{
m_pConnection = NULL;
TRACE(_T("Database CreateInstance failed"));
}

if (!SUCCEEDED(m_pRecordset.CreateInstance(__uuidof(Recordset))))
{
m_pRecordset = NULL;
TRACE(_T("Recordset CreateInstance Failed!"));
}

//打开数据库
CString strConnect = _T("Provider=Microsoft.Jet.OLEDB.4.0;Data Source= Demo.mdb");
if (!OpenDatabase(strConnect))
{
AfxMessageBox(_T("数据库打开失败。"));
return;
}

//打开记录集
if (!OpenRecordset(_T("SELECT * FROM DemoTable")))
{
AfxMessageBox(_T("记录集打开失败。"));
return;
}

}

CDemoDlg::~CDemoDlg()

{
m_pRecordset->Close();
m_pConnection->Close();

}

void CDemoDlg::DoDataExchange(CDataExchange* pDX)

{
CDialog::DoDataExchange(pDX);
//{{AFX_DATA_MAP(CDemoDlg)
//}}AFX_DATA_MAP

}

BEGIN_MESSAGE_MAP(CDemoDlg, CDialog)
//{{AFX_MSG_MAP(CDemoDlg)
ON_WM_SYSCOMMAND()
ON_WM_PAINT()
ON_WM_QUERYDRAGICON()
ON_BN_CLICKED(IDC_FIND, OnFind)
//}}AFX_MSG_MAP

END_MESSAGE_MAP()

/////////////////////////////////////////////////////////////////////////////

// CDemoDlg message handlers

BOOL CDemoDlg::OnInitDialog()

{
CDialog::OnInitDialog();

// Add "About..." menu item to system menu.

// IDM_ABOUTBOX must be in the system command range.
ASSERT((IDM_ABOUTBOX & 0xFFF0) == IDM_ABOUTBOX);
ASSERT(IDM_ABOUTBOX < 0xF000);

CMenu* pSysMenu = GetSystemMenu(FALSE);
if (pSysMenu != NULL)
{
CString strAboutMenu;
strAboutMenu.LoadString(IDS_ABOUTBOX);
if (!strAboutMenu.IsEmpty())
{
pSysMenu->AppendMenu(MF_SEPARATOR);
pSysMenu->AppendMenu(MF_STRING, IDM_ABOUTBOX, strAboutMenu);
}
}

// Set the icon for this dialog.  The framework does this automatically
//  when the application's main window is not a dialog
SetIcon(m_hIcon, TRUE);// Set big icon
SetIcon(m_hIcon, FALSE);// Set small icon

//初始化ListCtrl
CListCtrl* pListCtrl = (CListCtrl*)GetDlgItem(IDC_LIST);
pListCtrl->SetExtendedStyle(LVS_EX_FULLROWSELECT | LVS_EX_GRIDLINES);
pListCtrl->InsertColumn(1, _T("序号"), LVCFMT_CENTER, 80);
pListCtrl->InsertColumn(2, _T("姓名"), LVCFMT_CENTER, 100);
pListCtrl->InsertColumn(3, _T("年龄"), LVCFMT_CENTER, 100);

return TRUE;

}

void CDemoDlg::OnSysCommand(UINT nID, LPARAM lParam)

{
if ((nID & 0xFFF0) == IDM_ABOUTBOX)
{
CAboutDlg dlgAbout;
dlgAbout.DoModal();
}
else
{
CDialog::OnSysCommand(nID, lParam);
}

}

// If you add a minimize button to your dialog, you will need the code below

//  to draw the icon.  For MFC applications using the document/view model,

//  this is automatically done for you by the framework.

void CDemoDlg::OnPaint() 

{
if (IsIconic())
{
CPaintDC dc(this); // device context for painting

SendMessage(WM_ICONERASEBKGND, (WPARAM) dc.GetSafeHdc(), 0);

// Center icon in client rectangle
int cxIcon = GetSystemMetrics(SM_CXICON);
int cyIcon = GetSystemMetrics(SM_CYICON);
CRect rect;
GetClientRect(&rect);
int x = (rect.Width() - cxIcon + 1) / 2;
int y = (rect.Height() - cyIcon + 1) / 2;

// Draw the icon
dc.DrawIcon(x, y, m_hIcon);
}
else
{
CDialog::OnPaint();
}

}

// The system calls this to obtain the cursor to display while the user drags

//  the minimized window.

HCURSOR CDemoDlg::OnQueryDragIcon()

{
return (HCURSOR) m_hIcon;

}

BOOL CDemoDlg::OpenDatabase(LPCTSTR lpszConnect, long nOptions)

{
ASSERT(m_pConnection != NULL);
ASSERT(lpszConnect != NULL);
ASSERT(AfxIsValidString(lpszConnect));

//打开数据库连接
try
{
return SUCCEEDED(m_pConnection->Open(_bstr_t(lpszConnect), 
_T(""), _T(""), nOptions));
}
catch (_com_error& e)
{
TRACE(_T("%s\n"), e.ErrorMessage());
return FALSE;
}

}

BOOL CDemoDlg::CloseDatabase()

{
ASSERT(m_pConnection != NULL);

//关闭数据库连接
try
{
if (m_pConnection->State & adStateOpen) 
{
return SUCCEEDED(m_pConnection->Close());
}
else
{
return TRUE;
}
}
catch (_com_error& e)
{
TRACE(_T("%s\n"), e.ErrorMessage());
return FALSE;
} 

}

BOOL CDemoDlg::OpenRecordset(LPCTSTR lpszSource, long nCursorType, long nLockType, long nOptions)

{
ASSERT(m_pConnection != NULL);
ASSERT(m_pRecordset != NULL);
ASSERT(lpszSource != NULL);
ASSERT(AfxIsValidString(lpszSource));

//打开记录集
try
{
return (SUCCEEDED(m_pRecordset->Open(_variant_t(lpszSource),
m_pConnection.GetInterfacePtr(),
(CursorTypeEnum)nCursorType, 
(LockTypeEnum)nLockType,
nOptions)));
}
catch(_com_error e)
{
TRACE(_T("%s\n"), e.ErrorMessage());
return FALSE;
}

}

BOOL CDemoDlg::CloseRecorset()

{
ASSERT(m_pRecordset != NULL);

//关闭记录集
try
{
if (m_pRecordset->State & adStateOpen) 
{
return SUCCEEDED(m_pRecordset->Close());
}
else
{
return TRUE;
}
}
catch (_com_error e)
{
TRACE(_T("%s\n"), e.ErrorMessage());
return FALSE;
}

}

void CDemoDlg::OnFind() 

{
if (!(m_pRecordset->State & adStateOpen))
{
AfxMessageBox((_T("记录集未打开。")));
return;
}

//查找条件
CString strCriteria = _T("");
CString strName = _T("");
GetDlgItemText(IDC_NAME, strName);
strCriteria.Format(_T("NAME like '%s'"), strName);

//查找记录集
CListCtrl* pListCtrl = (CListCtrl*)GetDlgItem(IDC_LIST);
pListCtrl->DeleteAllItems();
if (m_pRecordset->BOF && m_pRecordset->adoEOF)
{
return;
}
m_pRecordset->MoveFirst();
int n = 0;
m_pRecordset->Find(_bstr_t(strCriteria), 0, adSearchForward);
while (!m_pRecordset->adoEOF)
{
_variant_t varValue;
CString strName = _T("");
int nAge = 0;

varValue = m_pRecordset->GetCollect(_variant_t(_T("NAME")));
if (varValue.vt != VT_NULL)
{
strName = varValue.bstrVal;
}
else
{
strName = _T("");
}

varValue = m_pRecordset->GetCollect(_variant_t(_T("AGE")));
if (varValue.vt != VT_NULL)
{
nAge = varValue.intVal;
}
else
{
nAge = 0;
}

//刷新ListCtrl
CString strText = _T("");
strText.Format(_T("%d"), n + 1);
pListCtrl->InsertItem(n, strText);
strText.Format(_T("%s"), strName);
pListCtrl->SetItemText(n, 1, strText);
strText.Format(_T("%d"), nAge);
pListCtrl->SetItemText(n, 2, strText);
n++;

m_pRecordset->Find(_bstr_t(strCriteria), 1, adSearchForward);
}

}

折叠起来看下函数；



代码就不解释了；函数含义比较明确；除了操作数据库，ADO方式还有COM相关操作；

效果：



VC在调试时，Data Source= Demo.mdb，这样的语句，访问的不是Debug目录下的Demo.mdb，是和Debug目录同级；

如果Debug目录同级没有数据库，则打开数据库失败；





工程下载
http://pan.baidu.com/s/1slEEOMD
Access工具下载
http://blog.csdn.net/bcbobo21cn/article/details/51000041
VC6下载
http://blog.csdn.net/bcbobo21cn/article/details/44200205

二 VC 访问 sqlite3

首先用sqlite3创建一个数据库，设备db；



创建表并插入数据；



接下来在VC6中新建一个控制台工程；

代码；

#include <stdio.h> 

#include <stdlib.h> 

#include <sqlite3.h> 

int column_names_printed = 0; 

void print_row(int n_values, char** values) 

{ 

    int i; 

    for (i = 0; i < n_values; ++i) { 

        printf("%10s", values[i]); 

    } 

    printf("\n"); 

} 

int print_result(void* data, int n_columns, char** column_values, char** column_names) 

{ 

    if (!column_names_printed) { 

        print_row(n_columns, column_names); 

        column_names_printed = 1; 

    } 

    

    print_row(n_columns, column_values); 

   

   return 0; 

} 

int main() 

{ 

    sqlite3 *db=NULL; 

    char *errMsg = NULL; 

    int rc; 

    

    rc = sqlite3_open("shebei.db", &db); 

    if( rc ){ 

        fprintf(stderr, "Can't open database: %s\n", sqlite3_errmsg(db)); 

        sqlite3_close(db); 

        exit(1); 

    } 

    else printf("open shebei.db successfully!\n"); 

    

    column_names_printed = 0; 

    rc = sqlite3_exec(db, "SELECT shebei.* FROM shebei;", print_result, NULL, &errMsg); 

    column_names_printed = 1; 

    printf("\n"); 

    

    printf("error code: %d\n", rc); 

    printf("error message: %s\n", errMsg); 

    sqlite3_close(db); 

    return 0; 

} 

注意如果如下的换行语句，

rc = sqlite3_exec(db, "CREATE TABLE students(number varchar(10), name varchar(10), \ 

                           sex varchar(6), age varchar(2));", NULL, NULL, NULL);

\之后如果有空格；则会出现；

Y:\dddd20\sqlitedemo1\demo1.cpp(39) : warning C4129: ' ' : unrecognized character escape sequence

删除空格即可；

现在我们有sqlite3.dll跟一个sqlite3.def文件，并没有用于VC++6.0的lib文件，可以利用sqlite3.def文件生成，步骤如下： 

  1.将sqlite3.h（D:\sqlite-amalgamation-3_6_23.zip）拷贝到C:\Program Files\Microsoft Visual Studio\VC98\Include目录下，这时编译可通过，但链接错误，因为没有LIB文件（） 

  2.启动一个命令行程序，进入VC的安装目录C:\Program Files\Microsoft Visual Studio\VC98\Bin，在这个目录下面有一个LIB.exe文件，使用它就能生成sqlite3.lib文件，将sqlite3.def文件放到相同目录，或者绝对路径也可以， 然后在命令行输入如下命令： 

   LIB /MACHINE:IX86 /DEF:sqlite3.def 

  该命令生成两个文件：sqlite3.lib和sqlite3.exp 

   运行该命令时，如果提示找不到MSPDB60.DLL文件，可从其它目录拷贝至Bin目录下 

  3.将生成的sqlite3.lib拷贝到Lib目录下,将sqlite3.dll拷贝到C:\WINNT\system32目录下 

   4.将sqlite3.lib加入到工程链接中，Project->Settings,Link选项卡，Object/library modules最后添入sqlite3.lib 

参阅：http://mxdxm.iteye.com/blog/634772

操作过程和完成结果如下图；



把环境配置好；编译运行程序；效果如下；



工程下载

sqlite相关下载，包括，h、Lib、dll文件;
http://pan.baidu.com/s/1slEEOMD

三 ADO访问数据库出现C2146、C2501

demodlg.h(25) : error C2146: syntax error : missing ';' before identifier 'm_pConnection'

demodlg.h(25) : error C2501: '_ConnectionPtr' : missing storage-class or type specifiers

demodlg.h(25) : error C2501: 'm_pConnection' : missing storage-class or type specifiers

在stdafx.h中加入如下语句再构建；

#import "c:\Program Files (x86)\common files\system\ado\msado15.dll"\
no_namespace\
rename("EOF", "adoEOF")

另外再看是否少了}；