最简单的dbhelper类

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Data.SqlClient;

using System.Data;

namespace MyBookShop.DAL {  

public class DBHelper     {       

  private static SqlConnection connection;

        public static SqlConnection Connection         {        

     get             {                 string connectionString = "server=.;database=MyBookShop;uid=sa;pwd=accp";

                if (connection == null)              

            {                     connection = new SqlConnection(connectionString);           

               connection.Open();

                }            

     else if (connection.State == ConnectionState.Closed)                 {                     connection.Open();                 }                 else if (connection.State == ConnectionState.Broken)                 {                     connection.Close();                     connection.Open();

                }

                return connection;             }         }

        public static int ExecuteCommand(string sql)         {             SqlCommand cmd = new SqlCommand(sql, 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 sql)         {             SqlCommand cmd = new SqlCommand(sql, 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 sql)         {             SqlCommand cmd = new SqlCommand(sql, 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 GetTableSet(string sql)         {             DataSet ds = new DataSet();             SqlCommand cmd = new SqlCommand(sql, Connection);             SqlDataAdapter da = new SqlDataAdapter(cmd);             da.Fill(ds);             return ds.Tables[0];

        }

        public static DataTable GetTableSet(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];         }

    } }