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;
         }
     }
 }