一些记录，已备后用

using System;
using System.Collections.Generic;
using System.Data;
using System.Data.SqlClient;
using MyBookShop.DAL;
using myRole.Models;

namespace myRole.DAL
{
    public class UserService
    {
        /// <summary>
        /// 获得所有的用户
        /// </summary>
        /// <returns></returns>
        public static IList<User> GetAllUser()
        {

            DataTable tbl = DBHelper.GetDataSet("select*from Users");
            IList<User> lis = new List<User>();
            foreach (DataRow row in tbl.Rows)
            {
                User user = new User();
                user.Uid = Int32.Parse(row["uid"].ToString());
                user.Uname = row["uname"].ToString();
                user.Upass = row["upass"].ToString();
                user.Rid = Int32.Parse(row["rid"].ToString());
                lis.Add(user);
            }
            return lis;
        }
        /// <summary>
        /// 用户登陆
        /// </summary>
        /// <param name="pass"></param>
        /// <param name="uname"></param>
        /// <returns></returns>
        public static User LoginUser(String pass, String uname)
        {
            String sql = "select*from Users where uname=@uname and upass=@upass";
            SqlParameter[] prr = new SqlParameter[] { 
            new SqlParameter("@uname",uname),
            new SqlParameter("@upass",pass)
            };
            SqlDataReader reader = DBHelper.GetReader(sql,prr);
            User user = new User();
            if (reader.Read())
            {
                user.Uid = Int32.Parse(reader["uid"].ToString());
                user.Uname = reader["uname"].ToString();
                user.Upass = reader["upass"].ToString();
                user.Rid = Int32.Parse(reader["rid"].ToString());
            }
            reader.Close();
            reader.Dispose();
            return user;
        }
        /// <summary>
        /// 根据id获取用户信息
        /// </summary>
        /// <param name="uid"></param>
        /// <returns></returns>
        public static User GetUserByUId(int uid)
        {

            String sql = "select*from Users where Uid=@uid";
            SqlParameter[] pp = new SqlParameter[] {
                new SqlParameter("@uid",uid)
            };
            SqlDataReader reader = DBHelper.GetReader(sql, pp);
            User user = new User();
            if (reader.Read())
            {
                user.Uid = Int32.Parse(reader["uid"].ToString());
                user.Uname = reader["uname"].ToString();
                user.Upass = reader["upass"].ToString();
                user.Rid = Int32.Parse(reader["rid"].ToString());
            }
            reader.Close();
            reader.Dispose();
            return user;
        }
        /// <summary>
        /// 根据角色获取所有的角色所拥有的权限
        /// </summary>
        /// <param name="rid"></param>
        /// <returns></returns>
        public static IList<Rules> GetRuleByRoleId(int rid)
        {
            IList<MidRoleAndRule> midRule= MidServices.GetRoleByRoleId(rid);
            IList<Rules> ruleList = new List<Rules>();
            foreach (MidRoleAndRule mid in midRule)
            {
             int ruid=mid.Ruid;//权限信息id
             Rules rule=RuleService.GetRuleByRuid(ruid);
             ruleList.Add(rule);
            }
            return ruleList;
        }
        /// <summary>
        /// 修改用户的角色
        /// </summary>
        /// <param name="roleId"></param>
        /// <returns></returns>
        public static int UpdateUserRole(int roleId,int uid)
        {
            String sql="update Users set rid=@rid where Uid=@uid";
            SqlParameter[] prar = new SqlParameter[] { 
            new SqlParameter("@rid",roleId),
            new SqlParameter("@uid",uid)
            };
          return  DBHelper.ExecuteCommand(sql,prar);
        }
    }
}

using System;
using System.Data;
using System.Data.SqlClient;

namespace MyBookShop.DAL
{
    public static class DBHelper
    {
        private static SqlConnection connection;
        public static SqlConnection Connection
        {
            get
            {
                string connectionString = "Data Source=localhost;Initial Catalog=myRole; uid=sa;Password=123";
                if (connection == null)
                {
                    connection = new SqlConnection(connectionString);
                    connection.Open();
                }
                else if (connection.State == System.Data.ConnectionState.Closed)
                {
                    connection.Open();
                }
                else if (connection.State == System.Data.ConnectionState.Broken)
                {
                    connection.Close();
                    connection.Open();
                }
                return connection;
            }
        }

        public static int ExecuteCommand(string safeSql)
        {
            SqlCommand cmd = new SqlCommand(safeSql, Connection);
            int result = cmd.ExecuteNonQuery();
            return result;
        }

        public static int ExecuteCommand(string sql, params SqlParameter[] values)
        {
            SqlCommand cmd = new SqlCommand(sql, Connection);
            cmd.Parameters.AddRange(values);
            return cmd.ExecuteNonQuery();
        }

        public static int GetScalar(string safeSql)
        {
            SqlCommand cmd = new SqlCommand(safeSql, Connection);
            int result = Convert.ToInt32(cmd.ExecuteScalar());
            return result;
        }

        public static int GetScalar(params SqlParameter[] values)
        {
            SqlCommand cmd = new SqlCommand();
            cmd.Connection = Connection;
            cmd.CommandText = "Pro_InsertOrder";
            cmd.CommandType = CommandType.StoredProcedure;
            cmd.Parameters.AddRange(values);
            int result = Convert.ToInt32(cmd.ExecuteScalar());
            return result;
        }

        public static int GetScalar(string sql, params SqlParameter[] values)
        {
            SqlCommand cmd = new SqlCommand(sql, Connection);
            cmd.Parameters.AddRange(values);
            int result = Convert.ToInt32(cmd.ExecuteScalar());
            return result;
        }

        public static SqlDataReader GetReader(string safeSql)
        {
            SqlCommand cmd = new SqlCommand(safeSql, Connection);
            SqlDataReader reader = cmd.ExecuteReader();
            return reader;
        }

        public static SqlDataReader GetReader(string sql, params SqlParameter[] values)
        {
            SqlCommand cmd = new SqlCommand(sql, Connection);
            cmd.Parameters.AddRange(values);
            SqlDataReader reader = cmd.ExecuteReader();
            return reader;
        }

        public static DataTable GetDataSet(string safeSql)
        {
            DataSet ds = new DataSet();
            SqlCommand cmd = new SqlCommand(safeSql, Connection);
            SqlDataAdapter da = new SqlDataAdapter(cmd);
            da.Fill(ds);
            return ds.Tables[0];
        }

        public static DataTable GetDataSet(string sql, params SqlParameter[] values)
        {
            DataSet ds = new DataSet();
            SqlCommand cmd = new SqlCommand(sql, Connection);
            cmd.Parameters.AddRange(values);
            SqlDataAdapter da = new SqlDataAdapter(cmd);
            da.Fill(ds);
            return ds.Tables[0];
        }
    }
}