实用的DBHelper帮助类

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

namespace BlogDAL
{
    public class DBHelper
    {
        private static SqlConnection con;
        private static SqlConnection Con {
            get {
                if (con == null)
                {
                    con = new SqlConnection(ConfigurationManager.ConnectionStrings["con"].ConnectionString);
                    con.Open();
                }
                else if (con.State == ConnectionState.Broken)
                {
                    con.Close();
                    con.Open();
                }
                else if (con.State == ConnectionState.Closed)
                {
                    con.Open();
                }
                return con;
            }
        }

        private static SqlCommand Cmd {
            get {
               return Con.CreateCommand();
            }
        }

        public static bool Update(string sql) {
            SqlCommand cmd = Cmd;
            cmd.CommandText = sql;
            return cmd. ExecuteNonQuery() > 0 ? true : false;
           
        }
        public static bool Update(string sql,SqlParameter[] pars)
        {
            SqlCommand cmd = Cmd;
            cmd.CommandText = sql;
            cmd.Parameters.AddRange(pars);
            return cmd.ExecuteNonQuery() > 0 ? true : false;
        }
        public static bool Update(string sql, SqlParameter[] pars,out SqlConnection con)
        {
            con = new SqlConnection(ConfigurationManager.ConnectionStrings["con"].ConnectionString);
            con.Open();
            SqlCommand cmd = con.CreateCommand();
            cmd.CommandText = sql;
            cmd.Parameters.AddRange(pars);
            return cmd.ExecuteNonQuery() > 0 ? true : false;
        }
        public static SqlDataReader SelectForDataReader(string sql)
        {
            SqlCommand cmd = Cmd;
            cmd.CommandText = sql;
            return cmd.ExecuteReader();
        }

        public static SqlDataReader SelectForDataReader(string sql,SqlParameter[] pars)
        {
            SqlCommand cmd = Cmd;
            cmd.CommandText = sql;
            cmd.Parameters.AddRange(pars);
            return cmd.ExecuteReader();
        }

        public static SqlDataReader SelectForDataReader(string sql, SqlParameter[] pars,out SqlConnection con)
        {
            con = new SqlConnection(ConfigurationManager.ConnectionStrings["con"].ConnectionString);
            con.Open();
            SqlCommand cmd = con.CreateCommand();
            cmd.CommandText = sql;
            cmd.Parameters.AddRange(pars);
            return cmd.ExecuteReader();
        }

        public static object SelectForScaler(string sql)
        {
            SqlCommand cmd = Cmd;
            cmd.CommandText = sql;
            return cmd.ExecuteScalar();
        }

        public static object SelectForScaler(string sql,SqlParameter[] pars)
        {
            SqlCommand cmd = Cmd;
            cmd.Parameters.AddRange(pars);
            cmd.CommandText = sql;
            return cmd.ExecuteScalar();
        }

    }
}