SQL Server支持三种备份方式

• 完全备份；
• 差异备份
• 事务日志备份

一般备份方式为，完全备份/每周，差异备份/每天，事务日志备份/按分钟计，这样可确保备份的高效性和可恢复性。

1. 完全备份

• 备份脚本

BACKUP DATABASE PCT TO DISK =‘D:\Company\Data\SQL Server\Backup\PCT.bak‘;

• 还原备份

RESTORE DATABASE PCT
FROM DISK = ‘D:\Company\Data\SQL Server\Backup\PCT.bak‘
WITH RECOVERY;

2. 差异备份

• 备份脚本

BACKUP DATABASE PCT TO DISK = ‘D:\Company\Data\SQL Server\Backup\PCT_Differential.bak‘ WITH DIFFERENTIAL;
GO

• 还原备份

在SQL Server中还原差异备份，需要先还原在差异备份时间点之前的一个完整备份，在还原完整备份时要加上NORECOVERY参数，SQL语句如下：

RESTORE DATABASE PCT
FROM  DISK = ‘D:\Company\Data\SQL Server\Backup\PCT.bak‘
WITH  FILE = 1,
NOUNLOAD,
STATS = 10,
NORECOVERY
GO

　　还原差异备份时，如果只有一个差异备份文件需要还原，无需使用NORECOVERY参数，SQL语句如下：

RESTORE DATABASE PCT
FROM  DISK = ‘D:\Company\Data\SQL Server\Backup\PCT_Differential.bak‘
WITH  FILE = 1,
NOUNLOAD,
STATS = 10
GO

　　如果有多个差异备份文件需要还原，除了最后一个差异备份文件，其他都需要加上NORECOVERY参数

事务日志备份

• 事务日志备份

BACKUP LOG PCT TO DISK =‘D:\Company\Data\SQL Server\Backup\PCT_Log.bak‘;

• 尾日志备份

BACKUP LOG PCT TO DISK =‘D:\Company\Data\SQL Server\Backup\PCT_TailLog.bak‘ WITH NORECOVERY;

• 完整恢复到失败点

USE master;
BACKUP DATABASE PCT
TO DISK =‘D:\Company\Data\SQL Server\Backup\PCT.bak‘
WITH INIT;
GO

-- Perform a transaction log backup of the Test database
BACKUP Log PCT
TO DISK =‘D:\Company\Data\SQL Server\Backup\PCT_log.bak‘
WITH INIT;
GO

-- ....<FAILURE OCCURS HERE>....

-- Back up the tail of the log to prepare for restore
BACKUP Log PCT
TO DISK =‘D:\Company\Data\SQL Server\Backup\PCT_taillog.bak‘
WITH NORECOVERY, INIT;
GO

-- Restore the full backup
RESTORE DATABASE PCT
FROM DISK = ‘D:\Company\Data\SQL Server\Backup\PCT.bak‘
WITH NORECOVERY;

-- Apply the transaction log backup
RESTORE LOG PCT
FROM DISK = ‘D:\Company\Data\SQL Server\Backup\PCT_log.bak‘
WITH NORECOVERY;

-- Apply the tail log backup
RESTORE LOG PCT
FROM DISK = ‘D:\Company\Data\SQL Server\Backup\PCT_taillog.bak‘
WITH NORECOVERY;

-- Recover the database
RESTORE DATABASE PCT
WITH RECOVERY;
GO

• 恢复到上次正确日志备份的时间点

-- FULL BACKUP at 2:00 AM
USE master ;
BACKUP DATABASE PCT
TO DISK = ‘D:\Company\Data\SQL Server\Backup\PCT.bak‘
WITH INIT ;
GO

-- LOG BACKUP 1 at 2:15 AM
USE master ;
BACKUP LOG PCT
TO DISK = ‘D:\Company\Data\SQL Server\Backup\PCT_log.bak‘
WITH INIT ;
GO

-- LOG BACKUP 2 at 2:30 AM
USE master ;
BACKUP LOG PCT
TO DISK = ‘D:\Company\Data\SQL Server\Backup\PCT_log2.bak‘
WITH INIT ;
GO

--有时候很遗憾，不能进行完整恢复：例如由于灾难当前事务日志不可用。这样的话，我们会需要还原数据库导最近日志备份的末尾
--如果灾难性故障发生在上午2:30，我们将需要恢复数据库到上午2:30的尾日志备份状态。
--因为不能进行尾日志备份，我们只能恢复到特定点，我们要使用STOPAT选项。

--RESTORE Full backup
RESTORE DATABASE PCT
FROM DISK = ‘D:\Company\Data\SQL Server\Backup\PCT.bak‘
WITH NORECOVERY;

--RESTORE Log file 1
RESTORE LOG PCT
FROM DISK = ‘D:\Company\Data\SQL Server\Backup\PCT_log.bak‘
WITH NORECOVERY, STOPAT = ‘Jan 01, 2020 12:00 AM‘;

--RESTORE Log file 2
RESTORE LOG PCT
FROM DISK = ‘D:\Company\Data\SQL Server\Backup\PCT_Log2.bak‘
WITH NORECOVERY, STOPAT = ‘Jan 01, 2020 12:00 AM‘;

--Recover the database
RESTORE DATABASE PCT
WITH RECOVERY;
GO