C++封装ado连接sqlserver增删查改

好的，下面是一个简单的示例代码，演示如何使用C++封装ADO连接SQL Server进行增删查改操作：

#include <iostream>
#include <windows.h>
#include <comdef.h>
#include <atlbase.h>
#import "C:\Program Files\Common Files\System\ado\msado15.dll" no_namespace rename("EOF", "adoEOF")

class CSQLServer
{
public:
    CSQLServer();
    ~CSQLServer();

    bool Connect(const std::string& strServer, const std::string& strDatabase,
        const std::string& strUser, const std::string& strPassword);
    void Disconnect();

    bool ExecuteNonQuery(const std::string& strSQL);
    bool ExecuteScalar(const std::string& strSQL, _variant_t& vtResult);

private:
    bool InitADO();
    void UninitADO();

private:
    _ConnectionPtr m_pConnection;
};

CSQLServer::CSQLServer()
{
    InitADO();
}

CSQLServer::~CSQLServer()
{
    UninitADO();
}

bool CSQLServer::Connect(const std::string& strServer, const std::string& strDatabase,
    const std::string& strUser, const std::string& strPassword)
{
    try
    {
        std::string strConnString = "Provider=SQLOLEDB.1;";
        strConnString += "Persist Security Info=False;";
        strConnString += "Data Source=" + strServer + ";";
        strConnString += "Initial Catalog=" + strDatabase + ";";
        strConnString += "User ID=" + strUser + ";";
        strConnString += "Password=" + strPassword + ";";

        m_pConnection->Open(strConnString.c_str(), "", "", adConnectUnspecified);
        return true;
    }
    catch (_com_error& e)
    {
        std::cout << "Connect failed, error message: " << e.Description() << std::endl;
        return false;
    }
}

void CSQLServer::Disconnect()
{
    m_pConnection->Close();
}

bool CSQLServer::ExecuteNonQuery(const std::string& strSQL)
{
    try
    {
        _RecordsetPtr pRecordset;
        pRecordset = m_pConnection->Execute(strSQL.c_str(), NULL, adCmdText);
        return true;
    }
    catch (_com_error& e)
    {
        std::cout << "ExecuteNonQuery failed, error message: " << e.Description() << std::endl;
        return false;
    }
}

bool CSQLServer::ExecuteScalar(const std::string& strSQL, _variant_t& vtResult)
{
    try
    {
        _RecordsetPtr pRecordset;
        pRecordset = m_pConnection->Execute(strSQL.c_str(), NULL, adCmdText);

        if (pRecordset->adoEOF == true)
        {
            vtResult.Clear();
            return false;
        }

        vtResult = pRecordset->Fields->GetItem((long)0)->Value;
        return true;
    }
    catch (_com_error& e)
    {
        std::cout << "ExecuteScalar failed, error message: " << e.Description() << std::endl;
        return false;
    }
}

bool CSQLServer::InitADO()
{
    try
    {
        HRESULT hr = CoInitialize(NULL);
        if (FAILED(hr))
        {
            std::cout << "CoInitialize failed" << std::endl;
            return false;
        }

        hr = m_pConnection.CreateInstance(__uuidof(Connection));
        if (FAILED(hr))
        {
            std::cout << "CreateInstance failed" << std::endl;
            CoUninitialize();
            return false;
        }

        return true;
    }
    catch (_com_error& e)
    {
        std::cout << "InitADO failed, error message: " << e.Description() << std::endl;
        return false;
    }
}

void CSQLServer::UninitADO()
{
    m_pConnection.Release();
    CoUninitialize();
}

int main()
{
    CSQLServer sqlServer;
    if (!sqlServer.Connect("localhost", "MyDatabase", "sa", "123456"))
    {
        return 0;
    }

    // 插入数据
    std::string strSQL = "INSERT INTO MyTable (Name, Age) VALUES ('Tom', 20)";
    sqlServer.ExecuteNonQuery(strSQL);

    // 修改数据
    strSQL = "UPDATE MyTable SET Age = 21 WHERE Name = 'Tom'";
    sqlServer.ExecuteNonQuery(strSQL);

    // 查询数据
    strSQL = "SELECT Age FROM MyTable WHERE Name = 'Tom'";
    _variant_t vtResult;
    if (sqlServer.ExecuteScalar(strSQL, vtResult))
    {
        std::cout << "Tom's age is " << (int)vtResult.intVal << std::endl;
    }
    else
    {
        std::cout << "Tom not found!" << std::endl;
    }

    // 删除数据
    strSQL = "DELETE FROM MyTable WHERE Name = 'Tom'";
    sqlServer.ExecuteNonQuery(strSQL);

    sqlServer.Disconnect();

    return 0;
}

上述代码使用`CSQLServer`类封装了ADO连接SQL Server的操作，并提供了插入、修改、查询、删除数据的方法。在使用时，只需要创建一个`CSQLServer`对象，调用`Connect`方法连接数据库，然后调用相应的方法执行SQL语句即可。

注意：上述代码使用了`#import`指令引入了`msado15.dll`库，需要确保该库已经安装在您的系统中。另外，需要链接`comsupp.lib`库。