oracle raw devices
1.LVM:
[root@vmfs ~]# pvdisplay
--- Physical volume ---
PV Name /dev/sdg
VG Name db_v4
PV Size 2.00 GB / not usable 0
Allocatable yes
PE Size (KByte) 4096
Total PE 511
Free PE 1
Allocated PE 510
PV UUID MlB8lE-H3DL-RCcf-p5Di-J6A2-INLc-zw328m
--- Physical volume ---
PV Name /dev/sdf
VG Name db_v3
PV Size 2.00 GB / not usable 0
Allocatable yes
PE Size (KByte) 4096
Total PE 511
Free PE 115
Allocated PE 396
PV UUID 2KsemU-DsQQ-GR8k-nnR2-Zm7M-nUCb-yXuUR5
--- Physical volume ---
相关文档：
首先查看数据库现有模式可使用以下语句
select name,log_mode from v$database;
也可以用下面的语句
archive log list；(该方法需要as sysdba)
对于非归档模式的数据库该为归档模式（主要以Oracle 10g为参考）使用以下步骤：
1. SQL> alter system set log_archive_dest_1='location=/oracle/oracle10g/log/archive ......
Ms sql 2000
drivername=com.microsoft.jdbc.sqlserver.SQLServerDriver
url=jdbc:microsoft:sqlserver://localhost:1433;DatabaseName=books
username=sa
password=sa
MySQL
drivername=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost/books
username=root
password=root
Oracle
drivername=orac ......
一、 常用日期数据格式
1.Y或YY或YYY 年的最后一位，两位或三位
SQL> Select to_char(sysdate,'Y') from dual;
TO_CHAR(SYSDATE,'Y')
--------------------
7
SQL> Select to_char(sysdate,'YY') from dual;
TO_CHAR(SYSDATE,'YY')
---------------------
07
SQL> Select to_char(sysdate,'YYY') from ......
--如何用grade表的资料去更新usertable表的资料（有关联的字段userid）
update usertable u set u.grade =
(select g.grade from grade g where g.userid = u.userid);
--如何使查询结果字段生成序号
select rownum, t.* from sm_t_pad_new t
--如何快速做一个和原表一样的备份表
create ......
