Oracle Database FAQ Summary (i)

1.1. Basic Concepts

Database: Service process (Database read-write log process, etc.)+ memory (memory occupied)+ database files (database, etc.).

table Space: The place where the data table is stored. A table space will have a corresponding . db file corresponding to

Example: You ate database after the process and the specific memory for him to read and write operations, this particular thing is an example. That is, the database concept of the rich process + memory, just this service process has been hit a SID This particular token.

Service: is used to mount the instance, of course there is no instance, the database service can also be run alone. When a server this time the option to load. But most of the things we call services are examples.

mode: Oracle also has a concept that this one, a schema is a database user of all the objects collectively.

a tablespace is a logical partition of a database, and a table space can belong to only one database. All database objects are stored in the specified table space. It has the following functions: (1) controlling the quota of table space occupied by the user, (2) controlling the disk space occupied by the user, (3) flexibly placing the table space, improving the input and output performance of the database; 5) log files and data are opened to improve the security of the database.

1.2. Switch Users

Su-oracle, the equivalent of re-login, at this time the user's home directory and PATH information will change.

Su Oracle, the user's home directory and path remain the original user's home directory and pathafterswitching to Oracle identity.

1.3. Date conversion Statements in the database

Selec sysdate,to_date (' 2008-11-10 10:36:11 ', ' yyyy-mm-dd hh24:mi:ss ') from dual;

Select To_char (update_date, ' Yyyy-mm-dd hh24:mi:ss ') from Td_topo. T_hn_temp_u2000_device;

1.4. database listening, logon, restart and other operations

Su-oacle # Switch to Oracle user

Lsnrctl Stop (TDSYSDB) stops monitoring

Lsnrctl Start monitoring, if also reported is not listening, turn off the firewall

1.5. database Startup and shutdown operations

Su-oracke switching to Oracle users

Sqlplus/as sysdba to log in to the database sysdba user

Sql>shutdown immediate; Close the database

Sql>quit exiting the database

Sql>startup/ Start Database

1.6. To Modify a database password

Su-oracle

Sqlplus/as SYSDBA

Alter profile default limit Password_reuse_time unlinited;

Alter profile default limit Passdord_reuse_max unlimited;

Alter user system identified by T_DPWDS8;

1.7. PL/SQL configuration

Tools -> Preferences->oracle-> Connections-> Check the connection

Plsql Configure the method for the four-bit Oracle :

http://blog.csdn.net/chen_zw/article/details/9292455/

1.8. query statement does not match Chinese problem

Execute the following query statement in the database to find out the current Chinese encoding

Select Userenv (' language ') from dual;

Simplified Chnese_china. Al32utf8

My Computer -> Properties-> Advanced system Settings-> Environment Variables-> System Variables- > New

nls= ' simplified Chnese_china. Al32utf8 '

after the increase is complete, restart PL/SQL can

1.9. database name, db instance name

To view the database name:

Show parameter db_name;

To view the DB instance name:

Show parameter instance_name;

To view the database listener name:

Cat/opt/oracle/oradb/home/network/admin/listener.ora

1.10. basic Information table in database

To view the details of each table space:

SELECT * from Dba_data_files;

SELECT * from Dba_tablespaces;

To view all user information:

SELECT * from Dba_users;

1.11. PL/SQL encoding Setup issues

Solve in PL/SQL, Chinese and date are garbled problems.

My Computer -> Properties-> Advanced system Settings-> Advanced-> Environment Variables

the environment variable the value of Nls_lang is set to:Chinese_china. ZHS16GBK or american_america. Al32utf8(do not mix the language with the code such as

Chinese_china. Al32utf8)

close and log back in PL/SQL client, making the settings effective.

Oracle Database FAQ Summary (i)