Oracle

1. Use "|" to connect multiple fields and merge them into a column.   2. Shielding duplicate rows   3. the pseudo column in Oracle is like a table column, but it is not stored in the table   Rownum> 3 because it cannot be found for the first

The reason for this error is that you have deleted a file from the Database Installation File, However, this error occurs when the server is restarted (accidentally powered off) on our server. However, the solution is the same. The following is a

This time, you must learn a new concept-VIEW ). As mentioned in previous notes, data objects include tables, views, sequences, indexes, and synonyms. The previous notes are all about table analysis, so this note will analyze the View world in depth.

Indexing is a powerful weapon to improve database query performance. Without an index, it is like a library without a book tag. It is more difficult to find a book you want than to climb to the sky. However, in the process of using indexes,

There are four types of SQL languages: Data Query Language DQL and data manipulation language DML, Data Definition Language DDL and data control language DCL.1. Data Query Language DQLThe basic structure of Data Query Language DQL is composed of

1. with grant option indicates that the user with the permission can continue to assign the permission. With admin option 2. Use profile to manage user passwords Create profile file name limit failed_login_attempts number of attempts

1. Role: A combination of Permissions Custom roles and predefined roles 2. Custom roles: dba, connect, and resource Predefined roles: 3. Delete permission: revoke XXX from XXX; 4. delete a user: drop user XXX cascade; Cascade: If you have

Oracle 11g RMAN recovery from different machines (linux to windows) Determine the data file, log file, and tempfile information of the original database. Select group #, status, type, member from v $ logfile;Col name format a65Select file #, name,

1. Delete service commandsThe specific operation method is: start -- run -- cmd, and enter the cmd command lineEnter the SC delete service name.Example: SC delete serv-u ServerQuery service input command: SC query service nameExample: SC query

1.1 symptom Description: failed to log on to the database. The system displays the following error message:% Sqlplus/as sysdba SQL*Plus: Release 10.2.0.4.0 - Production on Thu Aug 6 10:39:23 2009 Copyright (c) 1982, 2007, Oracle. All Rights

CursorInsufficient query results and records, difficult to express with variablesThe cursor can access the result set by row.Basic PrinciplesDML results are placed in the buffer zoneThe cursor is a pointer to the buffer.CategoryStatic cursorThe

Recently, all the company's operating systems have been upgraded to Windows 7. Our company has an ORACLE product software for Engineering Planning called Primavera Six (P6). So I need to migrate the P6 database from XP to the Win7 system. This is

Absolute Value Function () Dual; () Dual; (,) Dual; () Dual; Mod (,) dual; Ceil () dual; () Dual; (,) Dual; (,) Dual; Trunc (,) dual; Trunc (,) dual; (,), (,), (,) Dual; There are many numeric processing functions, such: SIN, SINH,

SELECT substr (v $ lock. sid, 1, 4) "SID ",Substr (username, 1, 12) "UserName ",Substr (object_name, 1,25) "ObjectName ",V $ lock. type "LockType ",Decode (rtrim (substr (lmode, 1, 4 )),'2', 'row-S (SS) ', '3', 'row-X (SX )','4', 'share', '5','s/Row-

Oracle numeric data types can store up to 38 bytes of precision. When Oracle numeric values are converted When the database is of the Common Language Runtime data type, there may be too many digits behind the decimal point, which leads to this

Today, I has added a datafile of an tablespace with 'alter tablespace tbs_name add datafile' + DATA '8g '. I have Ed a critical warning that the data guard standby machine done which cocould not synchronous the data after a period time. I viewed the

Recently encountered a connection to Oracle project problem, error such as: ORA-12519: TNS: no appropriate service handler found, it should be some of the project algorithm to all connections are occupied, there is no way to increase data

ALERT Log error message: Mon Jan 20 15:03:22 2014Incremental checkpoint up to RBA [0x442f. abd.0], current log tail at RBA [0x442f. 338a. 0]Mon Jan 20 15:08:13 2014Errors in

Indexing is efficient for querying a small number of databases in a large amount of data, but it is negative for DML operations: ① It has the greatest negative impact on insert operations, the more indexes the table has, the more indexes it updates,

1. Default users of the system 1) The sys user is a super user with the highest permissions, The sysdba role, and the create database permission. The default password of the user is sys.Logon statement: SQL> conn sys/sys as sysdba; 2) the system