SQL*Plus FAQ
What is SQL*Plus and where does it come from?
SQL*Plus is a command line SQL and PL/SQL language interface and reporting tool that ships with the Oracle Database Client and Server software. It can be used interactively or driven from scripts. SQL*Plus is frequently used by DBAs and Developers to interact with the Oracle database.
If you are familiar with other databases, sqlplus is equivalent to:
"sql" in Ingres,
"isql" in Sybase and SQL Server,
"sqlcmd" in Microsoft SQL Server,
"db2" in IBM DB2,
"psql" in PostgreSQL, and
"mysql" in MySQL.
SQL*Plus's predecessor was called UFI (User Friendly Interface). UFI was included in the first Oracle releases up to Oracle 4. The UFI interface was extremely primitive and, in today's terms, anything but user friendly. If a statement was entered incorrectly, UFI issued an error and rolled back the entire transaction (ugggh).
How does one use the SQL*Plus utility?
Start using SQL*Plus by executing the "sqlplus" command-line utility from the $ORACLE_HOME/bin directory. Some of the command line options:
userid/password@db -- Connection details
/nolog -- Do not login to Oracle. You will need to do it yourself.
-s or -silent -- start sqlplus in silent mode. Not recommended for beginners!
@myscript -- Start executing script called "myscript.sql"
Look at this example session:
sqlplus /nolog
SQL> connect scott/tiger
SQL> select * from tab;
SQL> disconnect
SQL> exit
Please note that one must prepare the environment before starting sqlplus.
Linux/ Unix example:
$ . oraenv
ORACLE_SID = [orcl] ? orcl
$ sqlplus scott/tiger
Windows Example:
Click on "Start" -> "Run" and enter "cmd"
C:> set ORACLE_SID=orcl
C:> sqlplus scott/tiger
or...
C:> sqlplus scott/tiger@orcl
What commands can be executed from SQL*
相关文档：
--创建链接服务器
exec sp_addlinkedserver 'ITSV ', ' ', 'SQLOLEDB ', '远程服务器名或ip地址 '
exec sp_addlinkedsrvlogin 'ITSV ', 'false ',null, '用户名 ', '密码 '
--查询示例
select * from ITSV.数据库名.dbo.表名
--导入示例
select * into 表 from ITSV.数据库名.dbo.表名
--以后不 ......
select Convert( varchar(20) , 时间字段 , 格式 ) from 表 如：select Convert(varchar(20),LOGIN_DATE,112) from dbo.C_PARTY_CLIENT 100：Jun 22 2009 12:00AM 101：06/22/2009 102：2009.06.22 103：22/06/2009 104：22.06.2009 105：22-06-2009 106：22
select Convert(varchar(20),<时间字段>,<格式>) f ......
SQL优化的原则是：将一次操作需要读取的BLOCK数减到最低。
调整不良SQL通常可以从以下几点切入：
检查不良的SQL，考虑其写法是否还有可优化内容；
检查子查询考虑SQL子查询是否可以用简单连接的方式进行重新书写；
检查优化索引的使用；
考虑数据库的优化器;
查询的一般规则
Ø ......
把Old数据库改为New数据库
1.打开“企业管理器”找到 Old数据库－－》右键－－》所有任务－－》分离数据库
2.到C:\Program Files\Microsoft SQL Server\MSSQL\Data下找到Old_Data.mdf和Old_log.ldf把Old_Data换成你想要的名字例如New.mdf、New.ldf
3.到企业管理器，找到 数据库 －－》右键－－》所有任务－－� ......
Oracle9i异常处理分为系统预定义异常处理和自定义异常处理两部分。
自定义异常处理
1.定义异常处理
declare 异常名 exception;
2.触发异常处理
raise 异常名
3.处理异常
exception
when 异常名1 then
异常处理语句段1;
when 异常名2 then
异常处理语句段2;
示例：
se ......
