First glance on oracle regular expression

作者: David, 于 May 4th,2009

Oracle 10g SQL/PLSQL引入了正则表达式语法。有以下几个内置函数：
REGEXP_LIKE
REGEXP_SUBSTR
REGEXP_INSTR
REGEXP_REPLACE
到了11g，oracle引入了一个新的函数：
REGEXP_COUNT
正则表达式的强大功能就不说了，在Oracle10g之前，很多复杂的字符串操作编程需要在客户端应用中实现。
下面简要介绍这几个函数：

?View Code TEXTSQL Element Category Description
————- ———- ————————————————————————————————-
REGEXP_LIKE Condition Searches a character column for a pattern.
[...]

May 4th, 2009 | Tags: , | Category: Oracle RDBMS, Programming | One comment

Maintaining Data Integrity

作者: David, 于 September 18th,2008

Maintaining Data Integrity
1.Methods to Guarantee Data Integrity
.Application code
.Database triggers
.Declarative integrity constraints

2.Types of Constraints
.NOT NULL
.UNIQUE
.PRIMARY KEY
.FOREIGN KEY
.CHECK

3.Constraint States
An integrity constraint can be enable(data is checked as it is entered or updated) or disabled(data that dose not confirm to the constraint’s rule is prevented from being entered).
An integrity constraint can be in one of the following states:
.DISABLE [...]

September 18th, 2008 | Tags: | Category: Oracle RDBMS | 留言

Autotrace in SQLPLUS(From Tom)

作者: David, 于 August 24th,2008

Here is what I like to do to get autotrace working:

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* cd $oracle_home/rdbms/admin
* log into sqlplus as system
* run >: @utlxplan
* run >: create public synonym plan_table for plan_table
* run >: grant all [...]

August 24th, 2008 | Tags: | Category: Oracle RDBMS | 留言

The SET ROLE statement

作者: David, 于 July 28th,2008

A role groups several privileges and roles, so that they can be granted to and revoked from users simultaneously. A role must be enabled for a user before it can be used by the user.
The SET ROLE statement allows you to enable or disable a role for a current session.
When a user logs into Oracle, [...]

July 28th, 2008 | Tags: , | Category: Oracle RDBMS | 留言

ORACLE(9i R2)控制文件-2

作者: David, 于 April 11th,2008

控制文件的数量设定取决数据库事务的数量大小。每一个事务对数据库所作的修改都会被记录在重做日志文件中，日志文件的大小决定于数据库可以丢失数据
的承受能力。如果数据库中的数据不重要，你可以承受丢失几个小时的数据，那么你就可以使用大重做日志文件，较少的日志文件数。
如果你不能承受任何数据的丢失，那么你就需要使用小的重做日志文件，多个日志文件。
在Oracle7, Oracle8-8i 和 Oracle9i,中最少要有两个重做日志文件组，建议使用三个。同时重做日志的镜像机制保证了重做日志文件几乎可以不遭受丢失。

April 11th, 2008 | Tags: | Category: Oracle RDBMS | 留言
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