对于经常在SQL*Plus 下工作的大师们而言，总是时不时查询SQL*Plus的帮助命令。着实太多了，记不住。SQL*Plus下直接提供了help命令来帮助描述所有命令的用法。嘎嘎，再也不用查SQL*Plus reference了。对于Oracle 10g缺省情况下，SQL*Plus的help手册并没有被安装，需要手动安装。Oracle 10/11g下采用相同的安装方式，下面来描述一下help的安装与使用。
1、安装sqlplus help
system@CNMMBO> help
SP2-0171: HELP system not available.
robin@SZDB:~> cd $ORACLE_HOME/sqlplus/admin/help --脚本路径位于ORACLE_HOME,sqlplus/admin/hlep目录下
robin@SZDB:/users/oracle/OraHome10g/sqlplus/admin/help> ls
helpbld.sql helpdrop.sql helpus.sql hlpbld.sql
robin@SZDB:/users/oracle/OraHome10g/sqlplus/admin/help> head -40 hlpbld.sql
--
-- Copyright (c) Oracle Corporation 1983, 2003. All Rights Reserved.
--
-- NAME
-- hlpbld.sql
--
-- DESCRIPTION
-- Builds the SQL*Plus HELP table and loads the HELP data from a
-- data file. The data file must exist before this script is run.
--
-- USAGE
-- To run this script, connect as SYSTEM and pass the datafile to be
-- loaded as a parameter e.g.
--
-- sqlplus system/<system_password> @hlpbld.sql helpus.sql
--
--
DEFINE DATAFILE = &1
--
-- Create the HELP table
--
DROP TABLE HELP;
CREATE TABLE HELP
(
TOPIC VARCHAR2 (50) NOT NULL,
SEQ NUMBER NOT NULL,
INFO VARCHAR2 (80)
) PCTFREE 0 STORAGE (INITIAL 48K PCTINCREASE 0);
GRANT SELECT ON HELP TO PUBLIC;
--
-- Insert the data into HELP.
--
@@&DATAFILE
system@CNMMBO> @$ORACLE_HOME/sqlplus/admin/help/hlpbld.sql helpus.sql
DROP TABLE HELP
*
ERROR at line 1:
ORA-00942: table or view does not exist
Table created.
Grant succeeded.
...
Commit complete.
View dropped.
2、help手册的用法
--查看刚刚创建的表已经添加了978行
system@CNMMBO> select count(*) from help;
COUNT(*)
----------
978
--直接在命令提示符下输入help，则给出SQL*plus help的用法:HELP|? [topic]
--help index or ? index则列出了当前sqlplus下所有可用命令
system@CNMMBO> help
HELP
----
Accesses this command line help system. Enter HELP INDEX or ? INDEX
for a list of topics. In iSQL*Plus, click the Help button to display
iSQL*Plus online help.
You can view SQL*Plus resources at http://otn.oracle.com/tech/sql_plus/
and the Oracle Database Library at http://otn.oracle.com/documentation/
HELP|? [topic]
--切换别的帐户来测试help是否可用
system@CNMMBO> conn goex_admin/xxxxx
Connected.
--下面的测试其他帐户也可以使用，因为在创建时创建了视图其授予了其他用户select 权限
goex_admin@CNMMBO> help index
Enter Help [topic] for help.
@ COPY PAUSE SHUTDOWN
@@ DEFINE PRINT SPOOL
/ DEL PROMPT SQLPLUS
ACCEPT DESCRIBE QUIT START
APPEND DISCONNECT RECOVER STARTUP
ARCHIVE LOG EDIT REMARK STORE
ATTRIBUTE EXECUTE REPFOOTER TIMING
BREAK EXIT REPHEADER TTITLE
BTITLE GET RESERVED WORDS (SQL) UNDEFINE
CHANGE HELP RESERVED WORDS (PL/SQL) VARIABLE
CLEAR HOST RUN WHENEVER OSERROR
COLUMN INPUT SAVE WHENEVER SQLERROR
COMPUTE LIST SET
CONNECT PASSWORD SHOW
--查看每一个命令的具体用法
--直接在提示符下help <command> 或者 ？ <command>
goex_admin@CNMMBO> help define
DEFINE
------
Specifies a substitution variable and assigns a CHAR value to it, or
lists the value and variable type of a single variable or all variables.
DEF[INE] [variable] | [variable = text]
-- Author : Robinson
-- Blog : http://blog.csdn.net/robinson_0612
goex_admin@CNMMBO> help accept
ACCEPT
------
Reads a line of input and stores it in a given substitution variable.
In iSQL*Plus, displays the Input Required screen for you to enter a
value for the substitution variable.
ACC[EPT] variable [NUM[BER] | CHAR | DATE | BINARY_FLOAT | BINARY_DOUBLE]
[FOR[MAT] format] [DEF[AULT] default] [PROMPT text | NOPR[OMPT]] [HIDE]
--有了它，再也不必为记不住的命令犯愁了。
更多参考
PL/SQL 联合数组与嵌套表
PL/SQL 变长数组
PL/SQL --> PL/SQL记录
