封装一个ado的数据库操作

vc数据库基本操作

对于vc连接数据库其实也很简单，vc深入详解中讲解的已经很清除了:

首先要先在头文件(stdafx.h)中加入(masdo15.dll拷贝到工程目录下)：

#import "msado15.dll" no_namespace rename("EOF","rsEOF")

查询与更新：

{
	CoInitialize(NULL);		//初始化组件
	
	_ConnectionPtr pConn(__uuidof(Connection));
	_RecordsetPtr  pRst(__uuidof(Recordset));

	pConn->ConnectionString = "provider=SQLOLEDB; Server=127.0.0.1; DataBase=数据库名字; uid=sa; pwd=数据库密码";		//访问的属性和方法，连接字串
	try
	{
		pConn->Open("", "", "", adConnectUnspecified);	//打开数据库的连接
	}
	catch(_com_error &e)
	{
		MessageBox(e.ErrorMessage());
		return;
	}
	
	char sql[50]="select * from userTable";
	char rest[10];

	pRst = pConn->Execute(sql, NULL, adCmdText);	//查询时候这样返回记录

	while(!pRst->rsEOF)
	{	
		strcpy(rest,(_bstr_t)pRst->GetCollect("sName"));
		MessageBox(rest);

		pRst->MoveNext();
	}	

	//更新代码
	pConn->Execute(sql, NULL, adCmdText)	//更新时候不需要返回值

	pRst->Close();
	pConn->Close();
	pRst.Release();
	pConn.Release();
	CoUninitialize();		//卸载组件
}

其实上面的语句执行也应该放到try{}catch()中，这里只是尽量简化操作，记录主体而已。

如果在实际应用中，上面的操作有点复杂，特别是众多try,catch.下面是我封装了一下这些操作的一个示例：

1.首先在stdafx中加入如下语句：

#import "msado15.dll" no_namespace rename("EOF","rsEOF")
	#include "DBsqlServer.h"
	extern CDBsqlServer*	g_pDB;

在程序初始化时候

::CoInitialize(NULL);//加载组件

if( !g_pDB->Initialize("127.0.0.1", "数据库密码") )

return FALSE;

//在程序退出时候卸载组件

::CoUninitialize();

2.查找与更新操作如下：

CSqlStatement *stmt = g_pDB->ExecuteSQL(strSQL);
		if( stmt != NULL && stmt->NextRow() )	//如果查询多个while(stmt->NextRow())
		{
			nCount = stmt->ValueInt(“字段名”);	//获取整形值
			str = stmt->ValueString(“字段名”);		//获取字符串值
			nCount = stmt->ValueInt();	//如果查询count值时候
		}
		delete stmt;//别忘了delete

封装的也很简单，代码如下：

.h

/************************************************************************/
/* 数据库封装类                                                         */
/* 1.CSalStatement用于取值												*/
/* 2.CDBsqlServer操作数据库												*/
/* 3.cpp文件中有个g_pDB全局变量，用这个来操作数据库						*/
/* 4.如果查询语句别忘了delete掉返回的结果集								*/
/* 5.(其实CSqlStatement重载'='也可以做成局部变量的形势，以后再处理吧)	*/
/* 用法:																*/
/* 1.stdafx.h或其它头文件下												*/
/*		#import "msado15.dll" no_namespace rename("EOF","rsEOF")		*/
/*		extern CDBsqlServer*	g_pDB;									*/
/* 2.程序初始化时候														*/
/*		::CoInitialize(NULL);											*/
/*		g_pDB->Initialize(dbName, dbPsw);								*/
/* 3.查询时候															*/
/*		CSqlStatement *stmt = g_pDB->ExecuteSQL(strSQL);				*/
/*		if( stmt != NULL && stmt->NextRow() )							*/
/*			nCount = stmt->ValueInt();									*/
/*		delete stmt;													*/
/*	 执行不返回结果的语句时:											*/
/*		g_pDB->UpdateSQL( strSQL );										*/
/* 4.程序退出时候别忘了: ::CoUninitialize();							*/
/************************************************************************/

#pragma once

class CSqlStatement
{
public:
	CSqlStatement(CString sql);
	~CSqlStatement();

	friend class CDBsqlServer;

	BOOL NextRow();

	long	ValueInt(CString  value = "");
	CString	ValueString(CString value);

protected:
	BOOL	Executesql();

protected:
	_RecordsetPtr m_recordset;
	BOOL	m_bFirst;
	CString m_strSQL;
};

class CDBsqlServer  
{
public:
	BOOL	Initialize(CString sDBname, CString sDBpsw);
	BOOL	UpdateSQL(const CString strSQL);

	CSqlStatement* ExecuteSQL(const CString strSQL);
	
	static CDBsqlServer *GetDBsqlServer();

protected:
	CDBsqlServer();
	virtual ~CDBsqlServer();

	BOOL	ConnectDB(CString sDBname, CString sDBpsw);

public:
	static _ConnectionPtr m_pConnection;

private:
	static CDBsqlServer *m_pDBsql;
};

.cpp

#include "stdafx.h"
#include "DBsqlServer.h"

CDBsqlServer *CDBsqlServer::m_pDBsql = NULL;
 _ConnectionPtr CDBsqlServer::m_pConnection = NULL;

CDBsqlServer* g_pDB = CDBsqlServer::GetDBsqlServer();		//用这个全局变量来进行数据库操作

CDBsqlServer::CDBsqlServer()
{
}

CDBsqlServer::~CDBsqlServer()
{
	m_pConnection->Close();
	m_pConnection.Release();	
}

CDBsqlServer* CDBsqlServer::GetDBsqlServer()
{
	if(NULL == m_pDBsql)
		return new CDBsqlServer;

	return m_pDBsql;
}

BOOL CDBsqlServer::Initialize(CString sDBname, CString sDBpsw)
{
	if ( (_T("") == sDBpsw) || (_T("")==sDBpsw) )
	{
		return FALSE;
	}
	return ConnectDB(sDBname, sDBpsw);
}

BOOL CDBsqlServer::UpdateSQL(const CString strSQL)
{
	try   
	{	
		_variant_t   vr; 
		m_pConnection->Execute((_bstr_t)strSQL,&vr,adCmdText);
	}   
	catch(_com_error& e)   
	{
		AfxMessageBox(e.ErrorMessage());
		return FALSE;
	} 

	return TRUE;
}

BOOL CDBsqlServer::ConnectDB(CString sDBname, CString sDBpsw)
{
	try                 
	{	
		m_pConnection.CreateInstance( __uuidof(Connection) );
		m_pConnection->PutConnectionTimeout((long)10);	//10秒超时
		
		CString  sConnect;
		sConnect.Format(_T("provider=SQLOLEDB; Server=%s; DataBase=ManModelDB; uid=sa; pwd=%s"), sDBname.GetBuffer(0), sDBpsw.GetBuffer(0));

		m_pConnection->ConnectionString = (_bstr_t)sConnect.GetBuffer(0);
		m_pConnection->Open("", "", "", adConnectUnspecified);	//打开数据库的连接
	}
	catch(_com_error e)
	{
		MessageBox(NULL, e.ErrorMessage(), _T("连接数据库失败"), 0);
		return FALSE;
	} 	
	return TRUE;
}

CSqlStatement* CDBsqlServer::ExecuteSQL(const CString strSQL)
{
	return new CSqlStatement(strSQL);	//获得这个指针后别忘了delete掉
}

//////////////////////////////////////////////////////////////////////////
//取值类

CSqlStatement::CSqlStatement(CString sql)
{
	m_recordset = NULL;
	m_bFirst = TRUE;
	m_strSQL = sql;
}

CSqlStatement::~CSqlStatement()
{
	if(m_recordset != NULL)
	{
		try
		{
			m_recordset->Close();
			m_recordset.Release();
		}
		catch(...){}
	}
}

BOOL CSqlStatement::Executesql()
{
	m_recordset.CreateInstance(__uuidof(Recordset));
	try
	{
		m_recordset = CDBsqlServer::m_pConnection->Execute((_bstr_t)m_strSQL,NULL,adCmdText);
	}
	catch(_com_error e)//捕捉异常
	{
		MessageBox(NULL, e.ErrorMessage(), "", 0);
		return FALSE;
	}

	if( (!m_recordset->rsEOF) && (NULL!=m_recordset) && (!m_recordset->BOF) ) 
		return TRUE;

	return FALSE;
}

BOOL CSqlStatement::NextRow()
{
	if( m_bFirst )
	{
		m_bFirst = FALSE;
		return Executesql();
	}

	m_recordset->MoveNext();
	if( (!m_recordset->rsEOF) && (NULL!=m_recordset) && (!m_recordset->BOF) ) 		
		return TRUE;

	return FALSE;	
}

long CSqlStatement::ValueInt(CString value)
{
	long nCount = 0;	
	_variant_t var = m_recordset->GetCollect(value.GetBuffer(0));

	if( VT_NULL != var.vt )
	{
		if ( (strcmp("", value)) == 0 )	//select count时候用此来取值
		{	
			nCount = var.lVal;
		}
		else
		{
			nCount = atol((char*)_bstr_t(var));
		}
	}

	return nCount;
}

CString CSqlStatement::ValueString(CString value)
{
	_variant_t var;		
	var = m_recordset->GetCollect(value.GetBuffer(0));

	if( VT_NULL != var.vt)
	{
		return CString( (char*)_bstr_t(var) );
	}
	else
	{
		return "";
	}
}

不知道是否有纰漏，还请大侠赐教....还有，这里使用了静态变量，所以值运行连接一个。