<add name="Connection str" connectionString="data source=.;pwd=12;uid=sa;database=12;" providerName="System.Data.SqlClient" />
//上面的是webconfig中的配置文件
    static string connstring_STR = "Connection str";
    public static DataSet ExeQuery(string Cmd)
    {
        //下面的DbFactory是微軟自帶的類庫，用於創建一個數據庫鏈接 
        //以後多用下DataBaseFactory
 
這個詞，
        Database db = DatabaseFactory.CreateDatabase(connstring_STR);
        DbConnection conn = db.CreateConnection();//創建一個Db的鏈接通道

        try
        {
            conn.Open();
            return db.ExecuteDataSet(CommandType.Text, Cmd);//這裏執行動作
        }

        finally
        {
            conn.Close();
            conn = null;
        }
    }

//加入事務，可以回滾
 public static void ExeNonQuery(string Cmd)
    {
        Database db = DatabaseFactory.CreateDatabase(connstring_TMS);
        DbConnection conn = db.CreateConnection();
        conn.Open();
        DbTransaction transaction = conn.BeginTransaction();

        try
        {
            db.ExecuteNonQuery(CommandType.Text, Cmd);
            transaction.Commit();
 

        }
        catch (Exception ex)
        {
            transaction.Rollback();
            throw ex;
        }
        finally
        {
            conn.Close();
            conn = null;
        }
    }

DataBaseFactory基礎了解