vs2005数据库访问

Question

<connectionStrings>
  <add name="MSPetShop4ConnectionString" connectionString="Data Source=WXHX-ACCORD;Initial Catalog=MSPetShop4;Integrated Security=True"
   providerName="System.Data.SqlClient" />
 </connectionStrings>web.config里面有这么一段，我应该怎么调用阿？
怎么才能付给DB_CONN_STRING            OleDbConnection conn = new OleDbConnection(DB_CONN_STRING);
            OleDbCommand cmd = new OleDbCommand("select * from Item ");
            conn.Open();

Answer 1

System.Configuration.ConnectionStringSettings DB_CONN_STRING;
        DB_CONN_STRING= System.Configuration.ConfigurationManager.ConnectionStrings["MSPetShop4ConnectionString"];
        if (DB_CONN_STRING != null)
        {
            conn = new OleDbConnection (DB_CONN_STRING);
        }

Answer 2

OleDbConnection  conn = new OleDbConnection (DB_CONN_STRING);

Answer 3

DB_CONN_STRING= System.Configuration.ConfigurationManager.ConnectionStrings["MSPetShop4ConnectionString"].ConnectionString;

Answer 4

DB_CONN_STRING = MSPetShop4ConnectionString" connectionString="Data Source=WXHX-ACCORD;Initial Catalog=MSPetShop4;Integrated Security=True
的话 是不能和OleDbConnection 一起用的？我应该怎么连？