Oracle

Usually when the current control file is lost, or if the current control file is inconsistent with the control file that needs to be recovered, we need to recreate a control file or use the Unsingbackup Controlfile method to recover the control file.

1, resource management, enabling parameters 09:44:54 sql> Show Parameter Resource NAME TYPE VALUE ------------------------------------ ----------- ------------------------------ Resource_limit Boolean FALSE Resource_manager_plan string 09:51:22

Quota management: object's maximum storage space, the user establishes the object on the table space, must obtain the quota on the corresponding tablespace. 1. View user disk quota usage information Sql> select

Use Oracle internal principles to describe the following procedures: 1, Sqlplus USER/PASSWD@ORCL 2, update t set a=1 where b= ' SS '; 3, commit; 4, exit 1, Sqlplus USER/PASSWD@ORCL (1), Client Sqlplus connection monitoring (2), listening to receive

One, SELECT1. Understanding | [] {} The meaning in the introduction of the command, as well as the data in the Basic Select query table, mainly using the Select command.SELECT *| {[DISTINCT] column|expression [alias],...} from table;In this way of

ORACLE provides both a cost based (costbased) and rule-based (rulebased) optimizer, referred to as the CBO and Rbo, to determine the execution plan for the query operation. How do I use the costbased optimizer to optimize query operations? How to

1. Definition Function: accepts 0 or more input parameters, has a return value, and the data type of the returned value is defined when the function is created. function Example 1 CREATE OR REPLACE FUNCTION Tax (p_empno in number) Return number

The Rank,dense_rank,row_number analytic functions provide similar functionality, but differ on the specifics. First of all, don't confuse rownum with Row_number. Let's look at the difference between these three functions in the following example.

First, the relevant query command 1.List database backed up by the current Rman rman> list incarnation; Rollup Queries: – If you have more than one backup file, use these two list commands to have a general understanding of the backup files. 1.1.

1. Use of high-speed storage devices to improve reading and writing capabilities, such as: EMC and NetApp, 2. If there is no data in the TAB1 table DROP TABLE TAB1; CREATE TABLE TAB1 as SELECT * from TAB2; And then when you create the index 3.

High Water Line All Oracle segments (segments, here, in order to understand the convenience, it is recommended that segment as a synonym for the table) has a cap to accommodate the data in the paragraph, we call this cap "high water mark" or HWM.

Database security and least privilege principles One, public permissions The public role is implicitly granted to each user. As long as any permissions are granted to public, the appropriate permissions are actually granted to everyone who can

Redo logs describe all changes to a block of data. This section mainly describes some of the operations when the database is opened to write logs. 3.1 Atomic Modifications The most basic operation of a database is to modify a block of data in an

Components of Oracle Architecture Oracle architecture includes a number of basic components we'll cover them in more detail below. 1, Oracle Server: Oracle server contains a variety of file structure, process structure and memory structure, but

Oracle Paging query statements can basically be applied in the format given in this article. Paging Query format: SELECT * FROM ( SELECT a.*, RowNum RN From (SELECT * from table_name) A WHERE RowNum ) WHERE RN >= 21 The most inner query

Because Oracle needs to prevent possible instance crashes at any time, Oracle will continue to locate this starting point during the normal operation of the database so that the data can be most effectively protected and recovered in an unexpected

In the recent software system to delete a record, it is necessary to link to delete many tables at the same time, there is a constraint relationship between them. So consider adding a constraint relationship when creating a table, and the details

The last time you talked about installing Oracle under Linux, you can use NETAC to configure the local naming of remote databases after installation. To connect Oracle databases under Perl, you must first install DBI and DBD for Oracle. Here's a

System Global area is a huge shared memory region that is seen as a large buffer pool for Oracle databases, where data can be shared by various processes in Oracle. Its size view statement: Sql> select * from V$SGA; V$sgastat, V$buffer_pool

1, installation Run script with sys user Utlxplan.sql The script to build this table is: (UNIX: $ORACLE _home/rdbms/admin, Windows:%oracle_home%\rdbms\admin) ultxplan.sql. Sql> connect sys/sys@colm2 as SYSDBA; Sql>