457.html

Jsp精华文章合集,JSP方面各种知识介绍

Cross-platform backups, even between different processor types, can be performed, providing the following <br>
sort order and character set restrictions are met: <br>
<br>
Usually, the sort order and character set of two servers must match for you to back up on one server and <br>
restore on the other. The exception to the sort order and character set matching between two servers is if <br>
both servers use a binary sort order. Then, the character sets can differ. <br>
It is possible to perform a backup on a server with a binary sort order and restore the back up onto a <br>
different server with a binary sort order. If the character sets are the same, all characters are <br>
interpreted identically between the two servers. If the character sets are different, however, any <br>
extended characters are interpreted differently on the two servers. Even though the stored binary value is <br>
the same, extended characters are interpreted differently depending on the installed character set. For <br>
example, the character A (ASCII value of 65) is interpreted the same for all character sets. If the <br>
character stored is ÷ (ASCII value of 246) on the first server with a character set of code page 437 <br>
(U.S. English), the second server with a character set of code page ISO 8859-1 (Latin 1 or ANSI), <br>
interprets the ÷ character as the &amp;ouml; character (ASCII value still 246). For more information, see <br>
Character Set. <br>
Backup File Format<br>
SQL Server backups can coexist on tape media with Windows NT backups because the SQL Server version 7.0 <br>
backup format conforms to Microsoft Tape Format (MTF), which is the same format used by Windows NT tape <br>
backups.<br>
<br>
Backup Types<br>
Here are the types of backups SQL Server supports: <br>
<br>
Full database backup, which backs up the entire database including the transaction log. <br>
Differential database backup, which is performed between full database backups. <br>
Transaction log backup. <br>
Use BACKUP LOG when changes made since either the last differential database backup or last full database <br>
backup are important to maintain. <br>
<br>
File(s) and Filegroup(s) backup. <br>
Backup devices used in a stripe set must always be used in a stripe set (unless reinitialized at some <br>
point with FORMAT) with the same number of devices. After a backup device is defined as part of a stripe <br>
set, it cannot be used for a single file backup unless FORMAT is specified. Similarly, a backup device <br>
that contains nonstriped backups cannot be used in a stripe set unless FORMAT is specified. Use FORMAT to <br>
split a striped backup set. If neither MEDIANAME nor MEDIADESCRIPTION is specified with FORMAT, the media <br>
header field corresponding to the blank item is empty. <br>
<br>
Use BACKUP to back up database files and filegroups instead of the full database when time constraints <br>
make a full database backup impractical. If you choose to back up a file instead of the full database, put <br>
procedures in place to assure that all files in the database are backed up regularly. Also, separate <br>
transaction log backups must be performed. After restoring a file backup, apply the transaction log to <br>
roll the contents of the file forward to make it consistent with the rest of the database. <br>
<br>
SQL Server must be able to read and write the device. Therefore, ownership and permission problems on the <br>
backup device’s physical file can interfere with a backup operation. sp_addumpdevice, which adds an entry <br>
for a device in the system tables, does not check file access permission. In fact, the physical resource <br>
is not accessed until a backup or restore in attempted. Any backup sets with passwords will not be able to <br>
be accessed. <br>
<br>
You cannot execute the BACKUP LOG statement while the trunc. log on chkpt. database option is enabled, nor <br>
can you execute it after enabling select into/bulkcopy and making unlogged changes to the database with <br>
SELECT INTO, UPDATETEXT, WRITETEXT, or a bulk-copy operation. Use BACKUP DATABASE instead.<br>
<br>
When a RESTORE is performed, the backup history tables are modified.<br>
<br>
<br>
--------------------------------------------------------------------------------<br>
<br>
Caution VOLUME is not an available option in SQL Server version 7.0. If VOLUME is specified, SQL Server <br>
returns an error message and halts the operation.<br>
<br>
<br>
--------------------------------------------------------------------------------<br>
<br>
Interaction of SKIP, NOSKIP, INIT, and NOINIT<br>
This table shows how the {INIT | NOINIT} and {NOSKIP | SKIP} clauses interact.<br>
<br>
  INIT NOINIT <br>
SKIP If the volume contains a valid** media header, verify the media password* and overwrite any backup <br>
sets on the media, preserving only the media header.<br>
<br>
If the tape media is empty or the disk media is nonexistent, write a media header and proceed. If the <br>
media is not empty, however, give feedback that this is not valid MTF media and abort the backup. If the <br>
volume contains a valid media header, verify the media password* and append the backup set, preserving all <br>
existing backup sets.<br>
<br>
If the volume does not contain a valid media header, an error occurs.<br>
<br>
If the tape media is empty or the disk media is nonexistent, write a media header and proceed. If the <br>
media is not empty, however, give feedback that this is not valid MTF media and cancel the backup. <br>
NOSKIP If the volume contains a valid media header, perform the following checks:<br>
<br>
Verify the media password***.<br>
If MEDIANAME was specified, verify that the given media name matches the media header’s media name.<br>
<br>
Verify that there are no unexpired backup set(s) already on the media.<br>
If there are, abort the backup.<br>
<br>
If these checks pass, overwrite any backup sets on the media, preserving only the media header.<br>
<br>
If the tape media is empty or the disk media is nonexistent, write a media header and proceed. If the <br>
media is not empty, however, give feedback that this is not valid MTF media and cancel the backup. If the <br>
volume contains a valid media header, verify the media password* and verify that the media name matches <br>
the given MEDIANAME, if any. If it matches, append the backup set, preserving all existing backup sets.<br>
<br>
If the volume does not contain a valid media header, an error occurs. <br>
* This capability is not supported by SQL Server version 7.0. <br>
** Validity includes the MTF version number and other header information. If the version specified is <br>
unsupported or an unexpected value, an error occurs.<br>
 <br>
*** The presence of a media password prevents the backup operation. To override the backup operation, <br>
specify FORMAT. <br>
<br>
<br>
--------------------------------------------------------------------------------<br>
<br>
Important To maintain backward compatibility, the DUMP keyword can be used in place of the BACKUP keyword <br>
in the BACKUP statement syntax. In addition, the TRANSACTION keyword can be used in place of the LOG <br>
keyword.<br>
<br>
<br>
--------------------------------------------------------------------------------<br>
<br>
Backup History Tables<br>
SQL Server includes these backup history tables that track backup activity : <br>
<br>
backupfile <br>
backupmediafamily <br>
backupmediaset <br>
backupset <br>
Permissions<br>
BACKUP DATABASE and BACKUP LOG permissions default to members of the db_owner fixed database role, who can <br>
transfer permissions to other users, and to members of the db_backupoperator fixed database role.<br>
<br>
Examples<br>
A. Back up the entire MyNwind database<br>
<br>
--------------------------------------------------------------------------------<br>
<br>
Note The MyNwind database is shown for illustration only.<br>
<br>
<br>
--------------------------------------------------------------------------------<br>
<br>
This example creates a backup device called MyNwind_1 that contains the full database backup of the <br>
MyNwind database.<br>
<br>
-- Create the backup device for the full MyNwind backup.<br>
<br>
USE master<br>
<br>
EXEC sp_addumpdevice 'disk', 'MyNwind_1',     'c:\mssql7\backup\MyNwind_1.dat'<br>
<br>
  <br>
<br>
-- Back up the full MyNwind database.<br>
<br>
BACKUP DATABASE MyNwind TO MyNwind_1<br>
<br>
  <br>
<br>
B. Back up the entire database and log<br>
This example creates both a full database and log backup. The database is backed up to a backup device <br>
called MyNwind_2, and then the log is backed up to a file called MyNwindLog1.<br>
<br>
-- Create the backup device for the full MyNwind backup.<br>
<br>
USE master<br>
<br>
EXEC sp_addumpdevice 'disk', 'MyNwind_2',     'c:\mssql7\backup\MyNwind_2.dat'<br>
<br>
  <br>
<br>
-- Back up the full MyNwind database.<br>
<br>
BACKUP DATABASE MyNwind TO MyNwind_2<br>
<br>
  <br>
<br>
-- Create the log backup device.<br>
<br>
USE master<br>
<br>
EXEC sp_addumpdevice 'disk', 'MyNwindLog1', <br>
<br>
    'c:\mssql7\backup\MyNwindLog1.dat'<br>
<br>
-- Update activity has occurred before this point.<br>
<br>
  <br>
<br>
-- Back up the log of the MyNwind database.<br>
<br>
BACKUP LOG MyNwind <br>
<br>
    TO MyNwindLog1<br>
<br>
<br>
 <br>
<br>
__________________<br>
<font color=red>真实源于生活！ </font><br>
请访问我们的网站： <br>
（VB爱好者乐园） <br>
<a href="http://www.vbgood.com" target=_blank>http://www.vbgood.com</a><br>
<a href="http://www.d1vb.com" target=_blank>http://www.d1vb.com</a><br>
<a href="http://61.128.97.225/vbgood/index.asp" target=_blank>http://61.128.97.225/vbgood/index.asp</a><br>
拥有1800多个资料！ </p>
</td>
  </tr>
</table>

<p>
<CENTER><a href="http://www.jsp001.com/forum/newreply.php?action=newreply&threadid=457">点这里对该文章发表评论</a></CENTER>
<p>该文章总得分是 <font color=red>0</font> 分，你认为它对你有帮助吗？
				[<a href=javascript:void(0) onclick=window.open("http://www.jsp001.com/forum/codeVote.php?threadid=457&intVote=4","","menubar=no,toolbar=no,location=no,directories=no,status=no,resizable=no,scrollbars=no,width=70,height=40,top=0,left=0")>非常多</a>](<font color=red>0</font>) 
				[<a href=javascript:void(0) onclick=window.open("http://www.jsp001.com/forum/codeVote.php?threadid=457&intVote=2","","menubar=no,toolbar=no,location=no,directories=no,status=no,resizable=no,scrollbars=no,width=70,height=40,top=0,left=0")>有一些</a>](<font color=red>0</font>) 
				[<a href=javascript:void(0) onclick=window.open("http://www.jsp001.com/forum/codeVote.php?threadid=457&intVote=1","","menubar=no,toolbar=no,location=no,directories=no,status=no,resizable=no,scrollbars=no,width=70,height=40,top=0,left=0")>无帮助</a>](<font color=red>0</font>) 
				[<a href=javascript:void(0) onclick=window.open("http://www.jsp001.com/forum/codeVote.php?threadid=457&intVote=-1","","menubar=no,toolbar=no,location=no,directories=no,status=no,resizable=no,scrollbars=no,width=70,height=40,top=0,left=0")>是灌水</a>](<font color=red>0</font>) </p>
<script language="javascript" src="http://www.jsp001.com/include/read_thread_script.php?threadid=457"></script>
<p><CENTER>
Copyright &copy; 2001 - 2009 JSP001.com . All Rights Reserved <P>

<IMG SRC="../image/jsp001_small_logo.gif" WIDTH="85" HEIGHT="30" BORDER=0 ALT="">
</CENTER></p>

</body>
</html>