A.List the prerequistites necessarey for database creation
1)确定数据库类型(OLTP or OLAP)
2)规划数据库架构, 如datafile, logfile 等存放磁盘, tablespace, 性能安全 (可以参考Oracle 建议的OFA:Optimal Felxible Arch)

用DBCA创建后的目录结构如下:
oradata (数据文件)
admin(pfile 和 各种Log)
oracle(纯oracle 软件)

3)认证方式a
   Local login (Login Linux first through Telnet, and then you can login oracle by the commond "conn / as sysdba " without password)
   password login (the password exist in passwd file, use " conn sys/oracle as sysdba" to login oracle, the password is required by oracle , 口 令文件是放在oracle 的dbs 目录下，只有属于dba这一组的用户可以采用os 方式认证登录。)
   Password File Create:
         a. create passwd file: "orapwd file=orapwtest password=boobooke entries=10"
         b. REMOTE_LOGIN_PASSWORDFILE=EXCLUSIVE add init arameter file
         c. add user to the password file
         d. grent .. to HR

B.create db by DBCA
profile 中设定好环境变量后，用户登录就自动动了。
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export ORACLE_BASE = ..
export ORACLE_HOME = ..
export ORACLE_SID=chris
export ORACLE_SID=chris/ocommon/nls/admin/data
export PATH = $ORACLE_HOME/bin:$PATH
export LD_LIBRARY_PATH=$ORACLE_HOME/lib:$LD_LIBRARY_PATH
dbca (if we need to invoke the dbca in comond mode ,we need to install Xmanager tool)
.... (其中有一步要求我们选择Archive mode)
#我们可以把刚才用dbca模式创建的方式存成模板，下次在创建新的db的时候指定这个模板就好了。

#How to delete db that created by dbca manually
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   rm -fR admin/chris/
   rm -fR oradata/chris/
   cd dbs
   rm -f orapwchris lkCHRIS spfilechris.ora
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C.Create db by manually

1. choose a unique instance and database name
   ORACLE_SID

2. choose a database character set

3. set operationg system environment variables
file:   bbk.env
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  export ORACLE_BASE = ..
  export ORACLE_HOME = ..
  export ORACLE_SID=chris/ocommon/nls/admin/data
  export OLACLE_NLS33=$ORACLE_HOME
  export PATH = $ORACLE_HOME/bin:$PATH
  export LD_LIBRARY_PATH=$ORACLE_HOME/lib:$LD_LIBRARY_PATH
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execute the file with commond:   ". ./bbk.env"

4. create the init parameter file (pfile)
creat pfile : initbbk.ora
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nb_name=bbk
....
#这里面如果有指定目录地址，我们得先前手动创建．
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5.create pwd fileorapw(sid):
[oracle@test oracle]$ orapwd file=/opt/oracle/product/9.2.0/dbs/orapwmydb password=bbk entries=5
这样就创建了一个针对mydb实例的密码文件.默认放到/opt/oracle/product/9.2.0/dbs目录下.此密码是sys用户的，并且在建库脚本了就不能指定sys的密码，会有冲突。

6. connect a db manually
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   sqlplus /nolog
   conn /  as sysdba
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7. create the spfile (oracle 会把control file 的位置回写到spfile中)
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    create spfile from pfile;
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8. start the instance in NOMOUNT stage
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    STARTUP NOMOUNT;
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6. create and execute the CREATE DBTABASE command
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#method 1:
    create database bbk;
#method 2:
    @crstudydb.sql
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Detail of crstudydb.sql :
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CREATE DATABASE study
   LOGFILE GROUP 1 ('/u01/app/oracle/oradata/study/redo01.log') SIZE 100M,
           GROUP 2 ('/u01/app/oracle/oradata/study/redo02.log') SIZE 100M,
           GROUP 3 ('/u01/app/oracle/oradata/study/redo03.log') SIZE 100M
   MAXLOGFILES 5
   MAXLOGMEMBERS 5
   MAXLOGHISTORY 1
   MAXDATAFILES 100
   MAXINSTANCES 1
   CHARACTER SET US7ASCII
   NATIONAL CHARACTER SET AL16UTF16
   DATAFILE '/u01/app/oracle/oradata/study/system01.dbf' SIZE 325M REUSE
   EXTENT MANAGEMENT LOCAL
   DEFAULT TEMPORARY TABLESPACE tempts1
      TEMPFILE '/u01/app/oracle/oradata/study/temp01.dbf'
      SIZE 20M REUSE
   UNDO TABLESPACE undotbs
      DATAFILE '/u01/app/oracle/oradata/study/undotbs01.dbf'
      SIZE 200M REUSE AUTOEXTEND ON NEXT 5120K MAXSIZE UNLIMITED;
------------------

7. run scripts to generate the data dictionary and accomplish post-creation steps(系统存储过程)
@?/rdbms/admin/catalog.sql
@?/rdbms/admin/catproc.sql
@?/sqlplus/admin/pupbld.sql
#?代表$ORACLE_HOME

8. create additional tablespaces as needed

a.
D.Create db by OMF(Oracle Manager Files)
这种方式不推荐使用。这里就不再详述！