dr可以实例化吗
public bool SearchRecord(out SqlDataReader dr)
        {
            SqlCommand sqlCom = new SqlCommand();
             = "select * from student";
            sqlCom.Connection = sqlCon;
            try
            {
                sqlCon.Open();
                dr = sqlCom.ExecuteReader(CommandBehavior.CloseConnection);
            }
            catch
            {
                return false;
            }
            return true;
        }
这里执行了catch由于dr没有实例化，因此出现异常，但是sqldatareader怎么才可以实例化啊，sqldatareader它是个抽象类啊