返回泛型集合的SqlDBHelper

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Entity;
using System.Diagnostics;
using System.Data.SqlClient;
using System.Data;
using System.Configuration;

namespace DAL
{
   public class SqlDBHelper
    {
        private string connectionString;
        public SqlDBHelper()
        {
           connectionString = System.Configuration.ConfigurationManager.ConnectionStrings["conn"].ConnectionString;
          //  connectionString = "Server=.;Integrated Security=true;Database=Northwind;uid=sa;pwd=123;";
        }
        [DebuggerNonUserCode]
        public List<TEntity> ReadAll<TEntity>(string sql,CommandType command, params SqlParameter[] parameters) where TEntity : EntityBase, new()
        {
            List<TEntity> entities = new List<TEntity>();

            using (SqlConnection conn = new SqlConnection(connectionString))
            {
                SqlCommand cmd = new SqlCommand(sql, conn);
                cmd.CommandType = command;
                cmd.Parameters.AddRange(parameters);

                conn.Open();
                using (SqlDataReader reader = cmd.ExecuteReader())
                {
                    while(reader.Read())
                    {
                        TEntity entity = new TEntity();
                        entity.ParseSqlDataReader(reader);
                        entities.Add(entity);
                    }
                }
            }

            return entities;
        }
    }
}