数据库是怎样连接的 详细步骤

namespace StudentDocument.DBUtility
{
public class SqlHelper
{
//private string connString = ConfigurationManager.ConnectionStrings["connectionStrings"].ConnectionString;
private static readonly string ConnetctionString = "Data Source=(local);Initial Catalog=StudentDoc;Integrated Security=True";

public static int ExecuteNonQuery(string cmdText, CommandType cmdType)
{
SqlCommand cmd = new SqlCommand();
using (SqlConnection conn = new SqlConnection(ConnetctionString)) {
int val = 0;
try
{
PrePareCommand(conn, null, cmd, cmdText, cmdType);
val = cmd.ExecuteNonQuery();
}
catch(Exception ex)
{
val = 0;
Console.WriteLine(ex.StackTrace);
}
//cmd.Parameters.Clear();
return val;
}
}
public static int ExecuteNonQuery(string cmdText)
{
return ExecuteNonQuery(cmdText, CommandType.Text);
}
public static SqlDataReader ExecuteReader(string cmdText, CommandType cmdType)
{
SqlCommand cmd = new SqlCommand();
SqlConnection conn = new SqlConnection(ConnetctionString);

try
{
PrePareCommand(conn, null, cmd, cmdText, cmdType);
SqlDataReader rdr = cmd.ExecuteReader(CommandBehavior.CloseConnection);
//cmd.Parameters.Clear();
return rdr;
}
catch
{
conn.Close();
throw;
}
}

public static SqlDataReader ExecuteReader(string cmdText)
{
return ExecuteReader(cmdText,CommandType.Text);
}

public static object ExecuteScalar(string cmdText, CommandType cmdType)
{
SqlCommand cmd = new SqlCommand();

using (SqlConnection conn = new SqlConnection(ConnetctionString))
{
PrePareCommand(conn, null, cmd, cmdText, cmdType);
object val = cmd.ExecuteScalar();
//cmd.Parameters.Clear();
return val;
}
}

public static DataTable GetDataTable(string cmdText, string srcTable)
{
return GetDataSet(cmdText, srcTable).Tables[srcTable];
}

public static DataSet GetDataSet(string cmdText, string srcTable)
{
SqlCommand cmd = new SqlCommand();
SqlDataAdapter adapter = new SqlDataAdapter(cmd);

using (SqlConnection conn = new SqlConnection(ConnetctionString)) {
PrePareCommand(conn, null, cmd, cmdText, CommandType.Text);
DataSet ds = new DataSet();
adapter.Fill(ds, srcTable);
return ds;
}
}

首先在stdafx.h中添加如下
#import "C:\Program Files\Common Files\System\ado\msado15.dll" no_namespace rename("EOF","rsEOF")
上面的路径根据你自己的更改

然后在你要查询的地方写如下代码：
CoInitialize(NULL);
_ConnectionPtr pConn(__uuidof(Connection));
_RecordsetPtr pRst(__uuidof(Recordset));
_CommandPtr pCmd(__uuidof(Command));
pConn->ConnectionString = "Driver=;Server=mySrvName;Option=16834;Database=mydatabase";
//这里的数据库连接字串根据你自己的版本写
pConn->Open("","","",adConnectUnspecified);
pRst = pConn->Execute("Select * from ...",NULL,adCmdText);
//写入的话是Insert，这个不用多说吧。
while(!pRst->rsEOF)
{

pRst->MoveNext();
}
pRst->Close();
pConn->Close();

pRst.Release();
pConn.Release();
pCmd.Release();
CoUninitialize();
具体地可参考孙鑫MFC视频教程20课，后半段。