Database Administrator

I. Official Website description Http://download.Oracle.com/docs/cd/E11882_01/server.112/e26088/functions088.htm#SQLRF00658 Purpose The LENGTH functionsreturn the length of char. LENGTH calculates length usingcharacters as defined by the input

In Linux, Oracle installs the configuration of One listener for two instances: Listener. ora file, # LISTENER. ORA Network Configuration File:/opt/oracle/product/9.2/network/admin/listener. ora# Generated by Oracle configuration tools. LISTENER

1. OOM Introduction Object-OrientedModel (OOM) object-oriented model. An OOM contains a series of packages, classes, interfaces, and their relationships. These objects form a class structure of all (or part) the logic of a software system design

First look at the table content Select name, pass from t1; 2. Method 1: Use the decode Function Select name, decode (pass, 'passs111', 'pass1', 'pass222', 'pass1', '', 'Password') from t1; Note: If you do not list the possible conditions in the

Loss of updates is a common and classic problem in data. During project creation, we may not notice this problem. However, this problem is very important and sometimes leads to serious results. Next we will discuss this missing update. 1. What is

One of the biggest challenges for developing multi-user database applications is to strive for the maximum concurrent access while ensuring that each user can read and modify data in a consistent manner. The maximum number of concurrent accesses

1.System PermissionsUnlimited tablespaceIs hidden inDba, resourceA system permission in the role. When the user obtains the role of dba or resource,The unlimited tablespace system permission is also implicitly authorized to the user. 2.System

Open Database flashback1. Check whether flashback is enabled for a database. There are two simple methods:(1) directly query the databaseSQL> select name, log_mode, flashback_on from v $ database; NAME LOG_MODE FLASHBACK_ON---------------------------

In practice, a large amount of data often needs to be imported to the current database table. The sqlldr Command provided by Oracle has a good meet requirement. During the use process, we found that if the default value is set in the Column on the

In the Oracle RAC environment, each node has multiple IP addresses: Public, Private, and Vip. What is the difference between these three IP addresses? Which occasions are used separately? Let's take a look at the answers from foreigners.1. private

(1) version: 1. Operating System: RHEL5.52.mysql-proxy-0.8.1-linux-rhel5-x86-64bit.tar.gz(2) installation 1. Extract mysql-proxy-0.8.1-linux-rhel5-x86-64bit.tar.gz directly.(Note: the source code has not been downloaded for self-compilation. Cause:

1 move ExperimentSQL> create table my_objects_move tablespace ASSM as select * from all_objects where rownum Table created   SQL> select value 2 from v $ mystat, v $ statname 3 where v $ mystat. statistic # = v $ statname. statistic # 4 and v $

1.1.Log & Checkpoint InnodbThe transaction log of isRedo log, AbbreviationLog,Save in Log FileIb_logfile *. Innodb also has another log Undo log, but the Undo log is stored in the shared tablespace (ibdata * file

Test. SQL: -- Create Test DataDrop table if exists T1;Create table T1 (Id bigint not null auto_increment,Pid bigint,Code varchar (255 ),Primary key (id));Insert into t1 (id, pid, code) values (1, null, '1 ');Insert into t1 (id, pid, code) values (2,

1. Prepare the 1.1.linux installation environment Version RHAS4: RedHat Enterprise Linux Advance Server 4.01. 2. Check the environment Hard Disk Space [Root @ localhost/] # df-h (Target installation directory)> 2G + 1G (package source

In Linux, RMAN is not completely restored for the database. An error occurred when executing recover database until time 'xxx: ORA-01841 (full) year must be between-4713 and + 4713/+ 9999 and must not be 0 Invalid format changes. The solution is

1 about undoThe database can have more than one undo tablespace;Undo segments can automatically grow, shrink on demand 2 about Oracle Data Dump export and importYou can change the table name during the import operation;You can override an existing

The Oracle user must perform operations on the Oracle server. The procedure is as follows: 1. Retrieve the font file simsun. ttc from windows 2. Create the fallback folder in the $ ORACLE_HOME/jdk/jre/lib/fonts directory. Command: mkdir fallback

Version Linux: RedHat 5.6 Oracle: 1, 10.2 Preparations before installation 1. Modify the operating system version. Before oracle is installed, it will verify the operating system version. If you do not know the version, it cannot be installed.

Syntax: REPLACE (char, search_string, replacement_string) Usage: convert all the string search_string in char to the string replacement_string without matching strings. Example: SQL> select REPLACE ('fgsgswsgs ', 'fk', 'J') from dual; return