C#實現SQL數據庫備份與還原

　　用Sql語句實現備份與還原操作時，最好不要使用需要備份或還原的數據庫連接，而使用master，否則可能會出現如下三個問題：(1)超時時間已到。在操作完成之前超時時間已過或服務器未響應。(2)  在向服務器發送請求時發生傳輸級錯誤。(provider:共享內存提供程序,error:0-系統無法打開文件。)  (3)從服務器接收結果時發生傳輸級錯誤。(provider:共享內存提供程序，error:0   -   系統無法打開文件。) 

　　還原或刪除sql server數據庫時，經常會出現：“因為數據庫正在使用，所以無法獲得對數據庫的獨占訪問權”，解決方法是在還原語句前執行"Alter database BookShop Set Offline With rollback immediate”，還原語句后執行“Alter database BookShop Set Online With Rollback immediate”。

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

namespace Util
{
    class DbHelper
    {
        public static string DbName { get; set; }

        private static SqlConnection SqlConnection = new SqlConnection("data source=.;Initial Catalog=master;integrated security=SSPI;");
        private static string SqlBackup = "BACKUP DATABASE BookShop TO DISK = 'F:\\ms\\src\\InternetBookstore\\DB\\" + DbName + ".bak'";
        private static string SqlRestore = "Alter database BookShop Set Offline With rollback immediate RESTORE DATABASE BookShop FROM DISK = 'F:\\ms\\src\\InternetBookstore\\DB\\" + DbName + ".bak' Alter database BookShop Set Online With Rollback immediate";
        private SqlCommand SqlCommandBackup     = new SqlCommand() { Connection = SqlConnection, CommandType = CommandType.Text, CommandText = SqlBackup };
        private SqlCommand SqlCommandRestore    = new SqlCommand() { Connection = SqlConnection, CommandType = CommandType.Text, CommandText = SqlRestore };

        public void DbBackup()
        {
            SqlConnection.Open();
            try
            {
                SqlCommandBackup.ExecuteNonQuery();
            }
            catch (Exception e)
            {
                string str = e.Message;
                SqlConnection.Close();
            }
            SqlConnection.Close();
        }

        public void DbRestore()
        {
            SqlConnection.Open();
            try
            {
                SqlCommandRestore.ExecuteNonQuery();
            }
            catch (Exception e)
            {
                string str = e.Message;
                SqlConnection.Close();
            }
            SqlConnection.Close();
        }
    }
}