源文件AdoConnection.cpp代码如下：

/*####################################################
    Filename:     AdoConnection.cpp
    ----------------------------------------------------
    Remarks:    ...
    ----------------------------------------------------
    Author:        成真
    Email:        anyou@sina.com
                anyou@msn.com
    Created:    20/1/2003 19:19
  ########################################################################*/
#include "stdafx.h"
#include "AdoConnection.h"
#include <math.h>

#ifdef _DEBUG
#undef THIS_FILE
static char THIS_FILE[]=__FILE__;
#define new DEBUG_NEW
#endif

/*########################################################################
              ------------------------------------------------
                                数值类型转换
              ------------------------------------------------
  ########################################################################*/
COleDateTime vartodate(const _variant_t& var)
{
    COleDateTime value;
    switch (var.vt) 
    {
    case VT_DATE:
        {
            value = var.date;
        }
        break;
    case VT_EMPTY:
    case VT_NULL:
        value.SetStatus(COleDateTime::null);
        break;
    default:
        value.SetStatus(COleDateTime::null);
        TRACE(_T("Warning: 未处理的 _variant_t 类型值; 文件: %s; 行: %d\n"), __FILE__, __LINE__);
    }
    return value;
}

COleCurrency vartocy(const _variant_t& var)
{
    COleCurrency value;
    switch (var.vt) 
    {
    case VT_CY:
        value = (CURRENCY)var.cyVal;
        break;
    case VT_EMPTY:
    case VT_NULL:
        value.m_status = COleCurrency::null;
        break;
    default:
        value.m_status = COleCurrency::null;
        TRACE(_T("Warning: 未处理的 _variant_t 类型值; 文件: %s; 行: %d\n"), __FILE__, __LINE__);
    }
    return value;
}

bool vartobool(const _variant_t& var)
{
    bool value = false;
    switch (var.vt)
    {
    case VT_DECIMAL:
    case VT_BOOL:
        value = var.boolVal ? true : false;
    case VT_EMPTY:
    case VT_NULL:
        break;
    default:
        TRACE(_T("Warning: 未处理的 _variant_t 类型值; 文件: %s; 行: %d\n"), __FILE__, __LINE__);
    }
    return value;
}

BYTE vartoby(const _variant_t& var)
{
    BYTE value = 0;
    switch (var.vt)
    {
    case VT_I1:
    case VT_UI1:
    case VT_DECIMAL:
        value = var.bVal;
        break;
    case VT_NULL:
    case VT_EMPTY:
        value = 0;
        break;
    default:
        TRACE(_T("Warning: 未处理的 _variant_t 类型值; 文件: %s; 行: %d\n"), __FILE__, __LINE__);
    }    
    return value;
}

short vartoi(const _variant_t& var)
{
    short value = 0;
    switch (var.vt)
    {
    case VT_BOOL:
        value = var.boolVal;
        break;
    case VT_UI1:
    case VT_I1:
        value = var.bVal;
        break;
    case VT_I2:
    case VT_UI2:
    case VT_DECIMAL:
        value = var;
        break;
    case VT_NULL:
    case VT_EMPTY:
        value = 0;
        break;
    case VT_BSTR:
        value = atoi((char*)(var.bstrVal));
        break;
    default:
        TRACE(_T("Warning: 未处理的 _variant_t 类型值; 文件: %s; 行: %d\n"), __FILE__, __LINE__);
    }    
    return value;
}

long vartol(const _variant_t& var)
{
    long value = 0;
    switch (var.vt)
    {
    case VT_BOOL:
        value = var.boolVal;
        break;
    case VT_UI1:
    case VT_I1:
        value = var.bVal;
        break;
    case VT_UI2:
    case VT_I2:
        value = var.iVal;
        break;
    case VT_I4:
    case VT_UI4:
        value = var.lVal;
        break;
    case VT_INT:
        value = var.intVal;
        break;
    case VT_R4:
        value = (long)(var.fltVal + 0.5);
        break;
    case VT_R8:
        value = (long)(var.dblVal + 0.5);
        break;
    case VT_DECIMAL:
        value = (long)var;
        break;
    case VT_CY:
        value = (long)var;
        break;
    case VT_BSTR://字符串
    case VT_LPSTR://字符串
    case VT_LPWSTR://字符串
        value = atol((LPCTSTR)(_bstr_t)var);
        break;
    case VT_NULL:
    case VT_EMPTY:
        value = 0;
        break;
    default:
        TRACE(_T("Warning: 未处理的 _variant_t 类型值; 文件: %s; 行: %d\n"), __FILE__, __LINE__);
    }
    return value;
}

double vartof(const _variant_t& var)
{
    double value = 0;
    switch (var.vt)
    {
    case VT_R4:
        value = var.fltVal;
        break;
    case VT_R8:
        value = var.dblVal;
        break;
    case VT_DECIMAL:
        value = (double)var;
        break;
    case VT_CY:
        value = (double)var;
        break;
    case VT_BOOL:
        value = var.boolVal;
        break;
    case VT_UI1:
    case VT_I1:
        value = var.bVal;
        break;
    case VT_UI2:
    case VT_I2:
        value = var.iVal;
        break;
    case VT_UI4:
    case VT_I4:
        value = var.lVal;
        break;
    case VT_INT:
        value = var.intVal;
        break;
    case VT_BSTR://字符串
    case VT_LPSTR://字符串
    case VT_LPWSTR://字符串
        value = atof((LPCTSTR)(_bstr_t)var);
        break;
    case VT_NULL:
    case VT_EMPTY:
        value = 0;
        break;
    default:
        value = 0;
        TRACE(_T("Warning: 未处理的 _variant_t 类型值; 文件: %s; 行: %d\n"), __FILE__, __LINE__);
    }
    return value;
}

CString vartostr(const _variant_t &var)
{
    CString strValue;
    
    switch (var.vt)
    {
    case VT_BSTR://字符串
    case VT_LPSTR://字符串
    case VT_LPWSTR://字符串
        strValue = (LPCTSTR)(_bstr_t)var;
        break;
    case VT_I1:
    case VT_UI1:
        strValue.Format("%d", var.bVal);
        break;
    case VT_I2://短整型
        strValue.Format("%d", var.iVal);
        break;
    case VT_UI2://无符号短整型
        strValue.Format("%d", var.uiVal);
        break;
    case VT_INT://整型
        strValue.Format("%d", var.intVal);
        break;
    case VT_I4: //整型
        strValue.Format("%d", var.lVal);
        break;
    case VT_I8: //长整型
        strValue.Format("%l", var.lVal);
        break;
    case VT_UINT://无符号整型
        strValue.Format("%d", var.uintVal);
        break;
    case VT_UI4: //无符号整型
        strValue.Format("%d", var.ulVal);
        break;
    case VT_UI8: //无符号长整型
        strValue.Format("%l", var.ulVal);
        break;
    case VT_VOID:
        strValue.Format("%8x", var.byref);
        break;
    case VT_R4://浮点型
        strValue.Format("%.4f", var.fltVal);
        break;
    case VT_R8://双精度型
        strValue.Format("%.8f", var.dblVal);
        break;
    case VT_DECIMAL: //小数
        strValue.Format("%.8f", (double)var);
        break;
    case VT_CY:
        {
            COleCurrency cy = var.cyVal;
            strValue = cy.Format();
        }
        break;
    case VT_BLOB:
    case VT_BLOB_OBJECT:
    case 0x2011:
        strValue = "[BLOB]";
        break;
    case VT_BOOL://布尔型

        strValue = var.boolVal ? "TRUE" : "FALSE";
        break;
    case VT_DATE: //日期型
        {
            DATE dt = var.date;
            COleDateTime da = COleDateTime(dt); 
            strValue = da.Format("%Y-%m-%d %H:%M:%S");
        }
        break;
    case VT_NULL://NULL值
        strValue = "";
        break;
    case VT_EMPTY://空
        strValue = "";
        break;
    case VT_UNKNOWN://未知类型
    default:
        strValue = "UN_KNOW";
        break;
    }
    return strValue;
}

/*########################################################################
             ------------------------------------------------
                    CAdoConnection class 构造/析构函数
             ------------------------------------------------
  ########################################################################*/

CAdoConnection::CAdoConnection()
{
    InitializeCriticalSection(&m_csConn);

    //创建 Connection 对象---------------------------
    //    m_pConnection.CreateInstance("ADODB.Connection");
    m_pConnection.CreateInstance(__uuidof(Connection));
    #ifdef _DEBUG
    if (m_pConnection == NULL)
    {
        m_strErrMsg.Format("Create Connection Object field! Please Init COM.\r\n");
        TRACE(m_strErrMsg);
    }
    #endif
    ASSERT(m_pConnection != NULL);
}

CAdoConnection::~CAdoConnection()
{
    DeleteCriticalSection(&m_csConn); //删除数据库连接临界区
    if (m_pConnection != NULL)
    {
        Release();
    }
}

/*========================================================================
    Name:        连接到数据源.
    -----------------------------------------------------
    Params:        [lpszConnect]: 连接字符串, 包含连接信息.
                [lOptions]:    可选. 决定该方法是以同步还是异步的方式连接数据
                        源. 可以是如下某个常量:
        [常量]                    [说明] 
        ----------------------------------
        adConnectUnspecified    (默认)同步方式打开连接. 
        adAsyncConnect            异步方式打开连接. Ado用 ConnectComplete 事
                        件来通知已经完成连接. 
==========================================================================*/
BOOL CAdoConnection::Open(LPCTSTR lpszConnect, long lOptions)
{
    ASSERT(m_pConnection != NULL);
    ASSERT(AfxIsValidString(lpszConnect));
    
    if (strcmp(lpszConnect, _T("")) != 0)
    {
        m_strConnect = lpszConnect;
    }

    if (m_strConnect.IsEmpty())
    {
        ASSERT(FALSE);
        return FALSE;
    }

    if (IsOpen()) Close();

    try
    {
        // 连接数据库 ---------------------------------------------
        SetConnectTimeOut(5);
        m_lOptions = lOptions;
        return (m_pConnection->Open(_bstr_t(LPCTSTR(m_strConnect)), "", "", lOptions) == S_OK);
    }
    catch (_com_error e)
    {
        m_strErrMsg.Format("Warning: 连接数据库发生异常. 错误信息: %s; 文件: %s; 行: %d\n",(LPCTSTR)e.Description(), __FILE__, __LINE__);
        TRACE(m_strErrMsg);
        return FALSE;
    } 
    catch (...)
    {
        m_strErrMsg.Format("Warning: 连接数据库时发生未知错误:");
        TRACE(m_strErrMsg);
    }
    return FALSE;
}

/*========================================================================
    Name:    连接 Oracle 数据库. 
    -----------------------------------------------------
    Params:        [dbsrc]:    Oracle 服务器名.
                [dbname]:    默认的数据库名.
                [user]:        用户名.
                [pass]:        密码.
==========================================================================*/
BOOL CAdoConnection::ConnectOracle(CString dbsrc, CString user, CString pass,UINT uiPort,long lOptions)
{
    CString strConnect = _T("Provider=MSDAORA; Data Source=") + dbsrc + 
                         _T("; User ID=") + user + 
                         _T("; Password=") + pass;
    m_byDBType = 1;// 数据库类型 0:SQL Server 1:Oracle
    return Open(LPCTSTR(strConnect), lOptions);
}

/*========================================================================
    Name:    连接 SQL SERVER 数据库. 
    -----------------------------------------------------
    Params:        [dbsrc]:    SQL SERVER 服务器名.
                [dbname]:    默认的数据库名.
                [user]:        用户名.
                [pass]:        密码.
==========================================================================*/
BOOL CAdoConnection::ConnectSQLServer(CString dbsrc, CString dbname, CString user, CString pass,UINT uiPort, long lOptions)
{
    CString strConnect = _T("Provider=SQLOLEDB.1; Data Source=") + dbsrc + 
                         _T("; Initial Catalog=") + dbname  +
                         _T("; User ID=") + user + 
                         _T("; PWD=") + pass;
    m_byDBType = 0;// 数据库类型 0:SQL Server 1:Oracle
    return Open(LPCTSTR(strConnect), lOptions);
}

/*========================================================================
    Name:    连接 ACCESS 数据库. 
    -----------------------------------------------------
    Params:        [dbpath]:    MDB 数据库文件路径名.
                [pass]:        访问密码.
===========================================================================*/
BOOL CAdoConnection::ConnectAccess(CString dbpath, CString pass, long lOptions)
{
    CString strConnect = _T("Provider=Microsoft.Jet.OLEDB.4.0; Data Source=") + dbpath;
    if (pass != _T("")) 
    {
        strConnect += _T(";Jet OLEDB:Database Password=") + pass + _T(";");
    }
    return Open(LPCTSTR(strConnect), lOptions);
}

/*========================================================================
    Name:    通过 udl 文件连接数据库. 
    -----------------------------------------------------
    Params:        [strFileName]:    UDL 数据库连接文件路径名.
==========================================================================*/
BOOL CAdoConnection::OpenUDLFile(LPCTSTR strFileName, long lOptions)
{
    CString strConnect = _T("File Name=");
    strConnect += strFileName;
    return Open(LPCTSTR(strConnect), lOptions);
}

/*========================================================================
    Name:    关闭与数据源的连接.
    -----------------------------------------------------
    Remarks: 使用 Close 方法可关闭 Connection 对象以便释放所有关联的系统资源. 
==========================================================================*/
void CAdoConnection::Close()
{
    try
    {
        if (m_pConnection != NULL && IsOpen()) 
        {
            m_pConnection->Close();
        }
    }
    catch (_com_error e)
    {
        m_strErrMsg.Format("Warning: 关闭数据库发生异常. 错误信息: %s; 文件: %s; 行: %d\n",(LPCTSTR)e.Description(), __FILE__, __LINE__);
        TRACE(m_strErrMsg);
    } 
}

/*========================================================================
    Name:    关闭连接并释放对象.
    -----------------------------------------------------
    Remarks: 关闭连接并释放connection对象.
==========================================================================*/
void CAdoConnection::Release()
{
    LeaveCriticalSection(&m_csConn);
    m_csConn.LockCount = -1;

    if (IsOpen()) Close();
    m_pConnection.Release();
}

/*========================================================================
    Name:        执行指定的查询、SQL 语句、存储过程等.
    ----------------------------------------------------------
    Remarks:    请参考 CAdoRecordSet 类的Open方法. 返回的 Recordset 对象始
            终为只读、仅向前的游标.
==========================================================================*/
_RecordsetPtr CAdoConnection::Execute(LPCTSTR lpszSQL, long lOptions)
{
    try
    {
        _RecordsetPtr Rs;
        Rs.CreateInstance(__uuidof( Recordset ));

        ASSERT(m_pConnection != NULL);
        ASSERT(AfxIsValidString(lpszSQL));
        if(IsOpen() == FALSE)
        {
            if(Open(m_strConnect,m_lOptions) == FALSE)
            {
                return FALSE;
            }
        }

        Rs = m_pConnection->Execute(_bstr_t(lpszSQL), NULL, lOptions);
        return Rs;
    }
    catch (_com_error e)
    {
        WORD wErrorCode;
        wErrorCode = e.WCode();
        // adErrInvalidConnection 3709 0x800A0E7D
        // 应用程序通过引用关闭或无效的 Connection 对象来请求对对象的操作。
        if(wErrorCode == adErrInvalidConnection)
        {
            if(m_pConnection != NULL)
                m_pConnection->Close();
            if(Open(LPCTSTR(m_strConnect),m_lOptions))
                Execute(lpszSQL, lOptions);
            else
            {
                return FALSE;
            }
        }

        m_strErrMsg.Format("Warning: Execute 方法发生异常. 错误信息: %s; 文件: %s; 行: %d\n",(LPCTSTR)e.Description(), __FILE__, __LINE__);
        TRACE(m_strErrMsg);
        return FALSE;
    } 
    return FALSE;
}

/*========================================================================
    Remarks:    请参考 CAdoRecordSet 类 Cancel 方法.
==========================================================================*/
BOOL CAdoConnection::Cancel()
{
    ASSERT(m_pConnection != NULL);
    try
    {
        return m_pConnection->Cancel();
    }
    catch (_com_error e)
    {
        m_strErrMsg.Format("Warning: Cancel 方法发生异常. 错误信息: %s; 文件: %s; 行: %d\n",(LPCTSTR)e.Description(), __FILE__, __LINE__);
        TRACE(m_strErrMsg);
        return FALSE;
    } 
    return FALSE;
}

/*========================================================================
    Name:    取得最后发生的错误信息.
==========================================================================*/
CString CAdoConnection::GetLastErrorText()
{
    ASSERT(m_pConnection != NULL);
    CString strErrors = "";
    try
    {
        if (m_pConnection != NULL)
        {
            ErrorsPtr pErrors = m_pConnection->Errors;
            CString strError;
            for (long n = 0; n < pErrors->Count; n++)
            {
                ErrorPtr pError = pErrors->GetItem(n);
                strError.Format(_T("Description: %s\r\nState: %s, Native: %d, Source: %s\r\n"),
                                (LPCTSTR)pError->Description,
                                (LPCTSTR)pError->SQLState,
                                         pError->NativeError,
                                (LPCTSTR)pError->Source);
                strErrors += strError;
            }
        }
        return strErrors;
    }
    catch (_com_error e)
    {
        m_strErrMsg.Format("Warning: GetLastError 方法发生异常. 错误信息: %s; 文件: %s; 行: %d\n",(LPCTSTR)e.Description(), __FILE__, __LINE__);
        TRACE(m_strErrMsg);
        return strErrors;
    } 
    return strErrors;
}

ErrorsPtr CAdoConnection::GetErrors()
{
    ASSERT(m_pConnection != NULL);
    try
    {
        if (m_pConnection != NULL)
        {
            return m_pConnection->Errors;
        }
        return NULL;
    }
    catch (_com_error e)
    {
        m_strErrMsg.Format("Warning: GetErrors 方法发生异常. 错误信息: %s; 文件: %s; 行: %d\n",(LPCTSTR)e.Description(), __FILE__, __LINE__);
        TRACE(m_strErrMsg);
        return NULL;
    } 
    return NULL;
}

ErrorPtr CAdoConnection::GetError(long index)
{
    ASSERT(m_pConnection != NULL);
    try
    {
        if (m_pConnection != NULL)
        {
            ErrorsPtr pErrors =  m_pConnection->Errors;
            if (index >= 0 && index < pErrors->Count)
            {
                return pErrors->GetItem(_variant_t(index));
            }
        }
        return NULL;
    }
    catch (_com_error e)
    {
        m_strErrMsg.Format("Warning: GetError 方法发生异常. 错误信息: %s; 文件: %s; 行: %d\n",(LPCTSTR)e.Description(), __FILE__, __LINE__);
        TRACE(m_strErrMsg);
        return NULL;
    } 
    return NULL;
}

/*========================================================================
    Name:        取得连接时间.
==========================================================================*/
long CAdoConnection::GetConnectTimeOut()
{
    ASSERT(m_pConnection != NULL);
    try
    {
        return m_pConnection->GetConnectionTimeout();
    }
    catch (_com_error e)
    {
        m_strErrMsg.Format("Warning: GetConnectTimeOut 方法发生异常. 错误信息: %s; 文件: %s; 行: %d\n",(LPCTSTR)e.Description(), __FILE__, __LINE__);
        TRACE(m_strErrMsg);
        return -1;
    } 
    return -1;
}

/*========================================================================
    Name:        设置连接时间.
==========================================================================*/
BOOL CAdoConnection::SetConnectTimeOut(long lTime)
{
    ASSERT(m_pConnection != NULL);
    try
    {
        m_pConnection->PutConnectionTimeout(lTime);
        return TRUE;
    }
    catch (_com_error e)
    {
        m_strErrMsg.Format("Warning: SetConnectTimeOut 方法发生异常. 错误信息: %s; 文件: %s; 行: %d\n",(LPCTSTR)e.Description(), __FILE__, __LINE__);
        TRACE(m_strErrMsg);
        return FALSE;
    } 
}

/*========================================================================
    Name:        取得默认数据库的名称.
==========================================================================*/
CString CAdoConnection::GetDefaultDatabase()
{
    ASSERT(m_pConnection != NULL);
    try
    {
        return CString(LPCTSTR(_bstr_t(m_pConnection->GetDefaultDatabase())));
    }
    catch (_com_error e)
    {
        m_strErrMsg.Format("Warning: GetDefaultDatabase 方法发生异常. 错误信息: %s; 文件: %s; 行: %d\n",(LPCTSTR)e.Description(), __FILE__, __LINE__);
        TRACE(m_strErrMsg);
        return CString(_T(""));
    } 
}

/*========================================================================
    Name:        取得 Connection 对象提供者的名称.
==========================================================================*/
CString CAdoConnection::GetProviderName()
{
    ASSERT(m_pConnection != NULL);
    try
    {
        return CString(LPCTSTR(_bstr_t(m_pConnection->GetProvider())));
    }
    catch (_com_error e)
    {
        m_strErrMsg.Format("Warning: GetProviderName 方法发生异常. 错误信息: %s; 文件: %s; 行: %d\n",(LPCTSTR)e.Description(), __FILE__, __LINE__);
        TRACE(m_strErrMsg);
        return CString(_T(""));
    } 
}

/*========================================================================
    Name:        取得 ADO 的版本号
==========================================================================*/
CString CAdoConnection::GetVersion()
{
    ASSERT(m_pConnection != NULL);
    try
    {
        return CString(LPCTSTR(_bstr_t(m_pConnection->GetVersion())));
    }
    catch (_com_error e)
    {
        m_strErrMsg.Format("Warning: GetVersion 方法发生异常. 错误信息: %s; 文件: %s; 行: %d\n",(LPCTSTR)e.Description(), __FILE__, __LINE__);
        TRACE(m_strErrMsg);
        return CString(_T(""));
    } 
}

/*========================================================================
    Name:        取得对象的状态(同 Recordset 对象的 GetState 方法).
    -----------------------------------------------------
    returns:    返回下列常量之一的长整型值.
        [常量]                [说明] 
        ----------------------------------
        adStateClosed        指示对象是关闭的. 
        adStateOpen            指示对象是打开的. 
    -----------------------------------------------------
    Remarks:        可以随时使用 State 属性取得指定对象的当前状态.
==========================================================================*/
long CAdoConnection::GetState()
{
    ASSERT(m_pConnection != NULL);
    try
    {
        return m_pConnection->GetState();
    }
    catch (_com_error e)
    {
        m_strErrMsg.Format("Warning: GetState 发生异常. 错误信息: %s; 文件: %s; 行: %d\n",(LPCTSTR)e.Description(), __FILE__, __LINE__);
        TRACE(m_strErrMsg);
        return -1;
    } 
    return -1;
}

/*========================================================================
    Name:    检测连接对象是否为打开状态.
==========================================================================*/
BOOL CAdoConnection::IsOpen()
{
    CString strLogFile = _T("AdoErr");
    CString strMsg;
    try
    {
        BOOL bResult;
        bResult = (m_pConnection != NULL && (m_pConnection->State & adStateOpen));
        
        return bResult;
    }
    catch (_com_error e)
    {
        strMsg.Format("Warning: IsOpen 方法发生异常. 错误信息: %s; 文件: %s; 行: %d\n",(LPCTSTR)e.Description(), __FILE__, __LINE__);
        TRACE(strMsg);

        return FALSE;
    } 
    return FALSE;
}

/*========================================================================
    Name:        取得在 Connection 对象中修改数据的可用权限.
    ----------------------------------------------------------
    returns:    返回以下某个 ConnectModeEnum 的值.
        [常量]                 [说明] 
        ----------------------------------
        adModeUnknown         默认值. 表明权限尚未设置或无法确定. 
        adModeRead             表明权限为只读. 
        adModeWrite             表明权限为只写. 
        adModeReadWrite         表明权限为读/写. 
        adModeShareDenyRead  防止其他用户使用读权限打开连接. 
        adModeShareDenyWrite 防止其他用户使用写权限打开连接. 
        adModeShareExclusive 防止其他用户打开连接. 
        adModeShareDenyNone  防止其他用户使用任何权限打开连接.
    ----------------------------------------------------------
    Remarks: 使用 Mode 属性可设置或返回当前连接上提供者正在使用的访问权限.
==========================================================================*/
ConnectModeEnum CAdoConnection::GetMode()
{
    ASSERT(m_pConnection != NULL);
    try
    {
        return m_pConnection->GetMode();
    }
    catch (_com_error e)
    {
        m_strErrMsg.Format("Warning: GetMode 发生异常. 错误信息: %s; 文件: %s; 行: %d\n",(LPCTSTR)e.Description(), __FILE__, __LINE__);
        TRACE(m_strErrMsg);
        return adModeUnknown;
    } 
    return adModeUnknown;
}

/*========================================================================
    Name:        设置在 Connection 中修改数据的可用权限. 请参考 GetMode 方法.
    ----------------------------------------------------------
    Remarks:    只能在关闭 Connection 对象时方可设置 Mode 属性.
==========================================================================*/
BOOL CAdoConnection::SetMode(ConnectModeEnum mode)
{
    ASSERT(m_pConnection != NULL);
    ASSERT(!IsOpen());

    try
    {
        m_pConnection->PutMode(mode);
    }
    catch (_com_error e)
    {
        m_strErrMsg.Format("Warning: SetMode 发生异常. 错误信息: %s; 文件: %s; 行: %d\n",(LPCTSTR)e.Description(), __FILE__, __LINE__);
        TRACE(m_strErrMsg);
        return FALSE;
    } 
    return TRUE;
}

/*========================================================================
    Name:        从数据源获取数据库信息.
    -----------------------------------------------------
    Params:        QueryType  所要运行的模式查询类型.
    -----------------------------------------------------
    returns:    返回包含数据库信息的 Recordset 对象. Recordset 将以只读、静态
            游标打开.
==========================================================================*/
_RecordsetPtr CAdoConnection::OpenSchema(SchemaEnum QueryType)
{
    ASSERT(m_pConnection != NULL);
    try
    {
        SetConnectTimeOut(5);
        return m_pConnection->OpenSchema(QueryType, vtMissing, vtMissing);
    }
    catch(_com_error e)
    {
        m_strErrMsg.Format("Warning: OpenSchema方法发生异常. 错误信息: %s; 文件: %s; 行: %d\n",(LPCTSTR)e.Description(), __FILE__, __LINE__);
        TRACE(m_strErrMsg);
        return NULL;
    } 
    return NULL;
}

/*########################################################################
              ------------------------------------------------
                                    事务处理
              ------------------------------------------------
  ########################################################################*/

/*========================================================================
    Name:        开始新事务.
    -----------------------------------------------------
    returns:    对于支持嵌套事务的数据库来说, 在已打开的事务中调用 BeginTrans 
    方法将开始新的嵌套事务. 返回值将指示嵌套层次: 返回值为 1 表示已打开顶层
    事务 (即事务不被另一个事务所嵌套), 返回值为 2 表示已打开第二层事务(嵌套
    在顶层事务中的事务), 依次类推.
    -----------------------------------------------------
    Remarks:    一旦调用了 BeginTrans 方法, 在调用 CommitTrans 或 RollbackTrans
    结束事务之前, 数据库将不再立即提交所作的任何更改.
        
==========================================================================*/
long CAdoConnection::BeginTrans()
{
    ASSERT(m_pConnection != NULL);
    try
    {
        return m_pConnection->BeginTrans();
    }
    catch (_com_error e)
    {
        m_strErrMsg.Format("Warning: BeginTrans 方法发生异常. 错误信息: %s; 文件: %s; 行: %d\n",(LPCTSTR)e.Description(), __FILE__, __LINE__);
        TRACE(m_strErrMsg);
        return -1;
    } 
    return -1;
}

/*========================================================================
    Name:        保存任何更改并结束当前事务.
    -----------------------------------------------------
    Remarks:    调用 CommitTrans 或 RollbackTrans 只影响最新打开的事务; 在
    处理任何更高层事务之前必须关闭或回卷当前事务.
==========================================================================*/
BOOL CAdoConnection::CommitTrans()
{
    ASSERT(m_pConnection != NULL);
    try
    {
        return SUCCEEDED(m_pConnection->CommitTrans());
    }
    catch (_com_error e)
    {
        m_strErrMsg.Format("Warning: CommitTrans 方法发生异常. 错误信息: %s; 文件: %s; 行: %d\n",(LPCTSTR)e.Description(), __FILE__, __LINE__);
        TRACE(m_strErrMsg);
        return FALSE;
    } 
    return FALSE;
}

/*========================================================================
    Name:        取消当前事务中所作的任何更改并结束事务.
==========================================================================*/
BOOL CAdoConnection::RollbackTrans()
{
    ASSERT(m_pConnection != NULL);
    try
    {
        return SUCCEEDED(m_pConnection->RollbackTrans());
    }
    catch (_com_error e)
    {
        m_strErrMsg.Format("Warning: RollbackTrans 方法发生异常. 错误信息: %s; 文件: %s; 行: %d\n",(LPCTSTR)e.Description(), __FILE__, __LINE__);
        TRACE(m_strErrMsg);
        return FALSE;
    } 
    return FALSE;
}

void CAdoConnection::Lock()
{
    EnterCriticalSection(&m_csConn);
}

void CAdoConnection::UnLock()
{
    LeaveCriticalSection(&m_csConn);
    //    m_csConn.LockCount = -1;
}

BYTE CAdoConnection::GetDBType()
{
    return m_byDBType;
}

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