VC＋ADO存取SQL SERVER

最新推荐文章于 2021-02-22 06:36:35 发布

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本文详细介绍了如何使用Visual C++和ADO组件连接SQLSERVER数据库，包括初始化COM库、创建连接对象、执行SQL查询及更新操作，并展示了在DEBUG模式下输出查询结果的方法。

VC＋ADO存取SQL SERVER
下面的代码是这样生成的
1)先生成一个MFC 对话框工程(名字叫Test)，并在stdafx.h加入下面一行，(注意路径)
#import "c:/program files/common files/system/ado/msado15.dll" no_namespace rename("EOF","adoEOF")
2)再在Test.h增加下面几个变量(protected)
_ConnectionPtr m_pConnection;//connection object's pointer
_CommandPtr m_pCommand; //command object's pointer
_ParameterPtr m_pParameter; //Parameter object's pointer
_RecordsetPtr m_pRecordset;
3)再修改Test.cpp中的InitInstance()
//初始化COM库
::AfxOleInit();
//连接数据库
HRESULT hr;
try
{
hr=m_pConnection.CreateInstance("ADODB.Connection");

if(SUCCEEDED(hr))
{
//如下的语句
char strConnection[100]=" Provider=sqloledb;Data Source=tulip;Initial Catalog=Pubs,User ID=sa; pwd=8818308";
m_pConnection->ConnectionTimeout=10;//User ID=sa; pwd=8818308;
hr=m_pConnection->Open("Provider=sqloledb; Data Source=tulip; Initial Catalog=Pubs","sa","8818308",adModeUnknown);
// hr=m_pConnection->Open("Provider=sqloledb; Server=tulip;DATABASE=Northwind;UID=sa;PWD=8818308","","",adModeUnknown);
// hr=m_pConnection->Open("driver={SQL Server}; Server=127.0.0.1;DATABASE=Northwind;UID=sa;PWD=8818308","","",adModeUnknown);
//得到结果
_variant_t RecordsAffected;
m_pRecordset.CreateInstance("ADODB.Recordset");
m_pRecordset=m_pConnection->Execute("select * from jobs",&RecordsAffected,adCmdText);

while (!m_pRecordset->adoEOF)
{
TRACE("job_id:%d,max_lvl:%d,min_lvl:%d/r/n",m_pRecordset->GetCollect(_variant_t((long)0)),m_pRecordset->GetCollect("max_lvl"),m_pRecordset->GetCollect("max_lvl"));
m_pRecordset->MoveNext();
}

//存放变量
_variant_t job_id,job_desc,max_lvl,min_lvl;
while(!m_pRecordset->adoEOF)
{
job_id=m_pRecordset->GetCollect(_variant_t((long)0));//得到第一项，也可以直接用字段名，见下
job_desc=m_pRecordset->GetCollect("job_desc");
max_lvl=m_pRecordset->GetCollect("max_lvl");
min_lvl=m_pRecordset->GetCollect("min_lvl");
///在DEBUG方式下的OUTPUT窗口输出记录集中的记录
if(job_id.vt != VT_NULL && job_desc.vt != VT_NULL && max_lvl.vt != VT_NULL && max_lvl.vt != VT_NULL)
TRACE("job_id:%d,max_lvl:%d,min_lvl:%d/r/n",job_id.lVal,/*job_desc,*/max_lvl.lVal,min_lvl.lVal);
m_pRecordset->MoveNext();
}
}
if (SUCCEEDED(hr))
{
hr=m_pCommand.CreateInstance("ADODB.Command");
m_pCommand->ActiveConnection=m_pConnection;
// char strQry[100] = "SELECT au_fname, au_lname, address, city "
//"FROM authors WHERE state = ";
// char strQry[100]="Select * from jobs where job_id =";
// strcat(strQry,"'");
// strcat(strQry,"12");
// strcat(strQry,"'");
// m_pCommand->CommandText="select * from jobs where jobs_id =";
m_pCommand->CommandText="Update jobs set job_desc=? where job_id=?";
m_pCommand->CommandType=adCmdText;
m_pParameter=m_pCommand->CreateParameter("job_desc",adVarChar,adParamInput,50,"网络2423423");
m_pCommand->Parameters->Append(m_pParameter);
m_pParameter=m_pCommand->CreateParameter("job_id",adSmallInt,adParamInput,10,"12");
m_pCommand->Parameters->Append(m_pParameter);
_variant_t vNULL;
vNULL.vt = VT_ERROR;
vNULL.scode = DISP_E_PARAMNOTFOUND;///定义为无参数

m_pCommand->Execute(&vNULL,&vNULL,adCmdText);
}
}
catch(_com_error e) //捕捉异常
{
CString errormessage;
errormessage.Format("连接数据库失败!/r/n错误信息:%s",e.ErrorMessage());
AfxMessageBox(errormessage);//显示错误信息
return FALSE;
}

// Standard initialization
// If you are not using these features and wish to reduce the size
// of your final executable, you should remove from the following
// the specific initialization routines you do not need.以下不变
4)运行此程序需要有sql支持，注意用户和密码

其实MSDN有许多有ADO的例子，具体路径是
MSDN->Platform SDK Documentation-->Data Services ->>Microsoft Data Access Components (MDAC)SDK -->Microsoft ActiveX Data Objects (ADO)--->ADO Programmer's Refernce -->ADO API Reference到了这里你就可以看有关ADO的资料了
5)再介绍一本有关ADO本质的好书
书名<ADO编程技术>
著者：David Sceppa
出版社：清华大学出版社
ISBN：7-900630-89-9