Oracle

The ORACLE tutorial is: ORACLE Application Experience (2 ). ------ Who is accessing the database?Select c. sid, c. serial #, c. username, a. object_id, B. object_name,C. program, c. status, d. name, c. osuserFrom v $ Locked_object,All_objects B,V $

The ORACLE tutorial is: oracle initialization parameter settings. Alter database DATAFILEd: \ ORANT \ DATABASE \ USER1ORCL. ora resize 1000 M;Create tablespace INDEX_DATA DATAFILEd: \ ORANT \ DATABASE \ INDEX_DATA SIZE 500 M;Alter database DATAFILEd:

The ORACLE tutorial is: Analysis and Solution of common ORACLE error codes (2 ). ORA-01578: Oracle data block upload upted (file # num, block # num) Cause: When ORACLE accesses a data block, due to 1. Hardware I/O errors; 2. Operating System I/O

The ORACLE tutorial is: in the ORACLE mobile database file. ---- ORACLE database consists of three types of files: data files, control files, and online log files. Due to disk space changes or database disk I/OPerformance adjustment. The database

The ORACLE tutorial is: how to accidentally delete the tablespace data file for Oracle7.X rollback. ---- 1. Introduction:---- The rollback segment is a part of the database, which records the database change information. Use this information to

A cluster is actually a group of tables, which are composed of multiple tables that share the same data block. Combining tables that are frequently used together into clusters can improve processing efficiency; a table in a cluster is called a

1. view the currently unlocked object Example: Execute select * from aa for update to lock the table aa;Method 1: query by SQLSelect 'alter system kill session ', ''' | trim (t2.sid) |', '| trim (t2.serial #) | ''';'From v $ locked_object t1, v $

Check whether the character set of some database servers and clients is different:Copy codeThe Code is as follows:Select * from nls_database_parameters;Select * from nls_instance_parameters;Select * from v $ nls_parameters t where t. PARAMETER =

During the past two weeks, I have been busy with the migration of databases. When I did not do it, I felt it was very easy, but I was dumpfounded when I did it. This tangle,Here we will first talk about the problem:1. Database Table Structure

In development, everyone should have done something similar to department management. Generally, there is a lower-level department (sub-department) under the next department. This level is similar to a tree. In this case, the Parent and Child

1. Estimate the execution Plan-Explain PlanThe Explain plan uses an SQL statement as the input to obtain the execution plan of the SQL statement and store the execution plan output to the schedule.First,Add the explain plan for statement before the

It is as follows: Control File: A file used to control the behavior of Data imports (the most important file ). Parameter file (optional) Data File: a flat file for storing source data Error file: when loading data, put the data that cannot be

First, let's talk about what they have in common:They are essentially an exclusive lock on resources and are all caused by concurrency (if the database has only one session, it cannot be locked ). Next we will focus on their differences: FirstThey

Therefore, in the daily maintenance of the database, if only one or two encounter ORA-01555 errors, generally ignore, But if you often encounter this error, make some adjustments to avoid this error from happening again. 1. Why is a ORA-01555 error?

Location of tnsnames. ora: D: \ Installed \ oracle \ product \ 11.1.0 \ db_1 \ NETWORK \ ADMIN \ tnsnames. ora, that is, in product You can log on to the database only after the listener is configured.Copy codeThe Code is as follows:TOTO

Copy codeThe Code is as follows:SELECTHeight,/* Height of the B-Tree */Blocks,/* Blocks in the index segment */Name,/* index name */Lf_rows,/* number of leaf rows in the index */Lf_blks,/* number of leaf blocks in the index */Del_lf_rows,/* number

1. create user username identified by password; // create a username and password for oracle and oracle2. grant connect, resource, dba to username; // authorize grant connect, resource, dba, sysdba to username;3. connect username/password.4. select

Copy codeThe Code is as follows:--> When the FROM clause contains multiple tables, select the table with the least number of records as the base table.--> Parsing the WHERE clause requires a bottom-up filter condition in order.--> ORACLE converts '*'

The oracle Import and Export solution is the main melody of backup and recovery, not dba. There is not much research on data import and export, and there is only a little bit of experience in the use process, which is briefly described here.Import

The LOB type can be BLOB or CLOB: BLOB is a Binary Large Object. It is suitable for storing non-text byte stream data (such as programs, images, audio and video ). CLOB, a Character Large Object, is related to Character sets and is suitable for