.net 在数据访问层中写一个DBhelper优化类

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Data.SqlClient;
using System.Data;
using Model;
namespace DAL
{
    class DBHelper
    {

        #region 获得连接对象 Connsql
        public static SqlConnection Connsql()
        {
            string sql = "server=.;database=vs;integrated security=sspi";
            SqlConnection conn = new SqlConnection(sql);
            return conn;
        }
        //执行 增加，删除，修改的sql语句
        #endregion


        #region 增加删除修改的sql语句执行方法  ExecuteNonQuery
        public static int ExecuteNonQuery(string sql,CommandType type,params SqlParameter[] sp)
        {
            SqlConnection conn = DBHelper.Connsql();
            conn.Open();

            SqlCommand sc = new SqlCommand(sql, conn);
            sc.CommandType = type;

            if(sp!=null)
            {
                foreach (SqlParameter p in sp)
                {
                    sc.Parameters.Add(p);
                }
            }
            int i = sc.ExecuteNonQuery();
            conn.Close();
            return i;
        }
        #endregion

        #region 数据库返回一个值时的sql语句执行方法
        public static Object ExecuteScalar(string sql,CommandType type, params SqlParameter[] paras)
        {
            SqlConnection conn = DBHelper.Connsql();
            conn.Open();
            SqlCommand  sc = new SqlCommand(sql,conn);
            sc.CommandType=type;
            
            if(paras!=null)
            {
            foreach(SqlParameter s in paras )
            {
            sc.Parameters.Add(s);
            }           
            }
            object result = sc.ExecuteScalar();
            conn.Close();
            return result;
        }
        #endregion

        #region 数据库返回多行记录的执行方法
        public static SqlDataReader ExecuteDataReader(string sql,CommandType type,params SqlParameter[] paras) 
        {
            SqlConnection conn = DBHelper.Connsql();
            conn.Open();
            SqlCommand sc = new SqlCommand(sql,conn);
            sc.CommandType = type;

            if (paras != null)
            {
                foreach (SqlParameter s in paras)
                {
                    sc.Parameters.Add(s);
                }
            }
            SqlDataReader dr = sc.ExecuteReader(CommandBehavior.CloseConnection);
            return dr;
        }
        #endregion

        #region 返回一个数据集时执行方法
        public static DataSet ExecuteDataSet(string sql,CommandType type,params SqlParameter [] paras)
        {
            SqlConnection conn = DBHelper.Connsql();
            conn.Open();
            SqlCommand sc = new SqlCommand(sql,conn);
            sc.CommandType = type;

            if (paras != null)            
            {
                foreach(SqlParameter s in paras)
                {
                    sc.Parameters.Add(s);
                }
            }
            SqlDataAdapter sda = new SqlDataAdapter(sc);
            DataSet ds = new DataSet();
            sda.Fill(ds);
            return ds;
        }
        #endregion

     

    }
}

 int result =(int)this.ExecuteScalar("select count(*) from UserAccount", CommandType.Text);

   DataSet ds = ExecuteDataSet("select * from UserAccount", CommandType.Text); 
   return ds.tables[0];

  #region 将数据填充到List集合中
       public List<tbSpecialty> GettbSpecialty() 
       {
           List<tbSpecialty> sp = new List<tbSpecialty>();
           SqlDataReader dr = DBHelper.ExecuteDataReader("select * from tbSpecialtyInfo", CommandType.Text);
               while(dr.Read())
               {
                   tbSpecialty tsp = new tbSpecialty();
                   tsp.SpecialtyName = dr["SpecialtyName"].ToString();               
                   sp.Add(tsp);
               }
               dr.Close();
               return sp;
       }
       #endregion

#region 
       public int AddtbSpecialty(tbSpecialty sp)
       {
           string sql = "insert into tbSpecialtyInfo values(@name,@remark)";
           SqlParameter p1 = new SqlParameter("@name", sp.SpecialtyName);
           SqlParameter p2 = new SqlParameter("@remark",sp.Remark);
           int result = DBHelper.ExecuteNonQuery(sql, CommandType.Text, p1, p2);
           return result;
       }
       #endregion