no rows selected

With the previous effort, all the jobs in the database are back to normal, there are no long-running sessions that hold locks, and there are no long-running transactions in the transaction view: Sql> SELECT instance_name from v$instance;

 1. Description of unique constraints on the official website Http://download.oracle.com/docs/cd/E11882_01/server.112/e16508/datainte.htm#CNCPT1642   Uniquekey constraint requires that every value in a column or set of columns beunique. no rows of a

In the database, a null value is used to indicate that the actual value is unknown or meaningless. In a table, if a column in a row has no value, it is called NULL ). A null value can be returned for any data type column as long as the non-NULL or

The error of indexing using indexes six: indexing all columns We know that indexing is an effort to improve query efficiency, but it should also be noted that indexes increase the cost of DML operations (INSERT, UPDATE, delete), and that most

About ROWID: When you insert a row of data into a table, ORACLE automatically adds a ROWID to the row. Each row has a unique ROWID. ORACLE uses ROWID to locate the row. ROWID is not explicitly stored as a column (a pseudo column -- instead of the

Generally, full-text indexes are mostly used in OLAP environments. Full-text indexes are good at quick word search. 1. Comparison between full-text indexes and ordinary B _tree indexes SQLcreatetablet1 (idint, namevarchar (10); Tablecreated.

About ROWID: When a user inserts a row of data into a table, Oracle automatically adds a rowid to the row, and each row has a unique rowid,oracle that uses ROWID to locate the data row. ROWID is not explicitly stored as a column of values

In the Oracle 10g database, a database object with a Recycle Bin (Recycle bin) was introduced.The Recycle Bin, in principle, is a data dictionary table that places the user's dropped database object information. Objects that are dropped by the user

The title is longer, but only in this way can the problem be described clearly. The problem is described in detail as, in First_rows optimization mode, the session sort and comparison method is set to semantic mode, that is, ignoring the case mode,

RAC creates a DBlink and uses impdp to extract data from the source database. Then it creates a dblink [plain] viewplaincopyprint? [Oracle @ zhongwc1 ~] $ Sqlplusassysd RAC creates a DBlink and uses impdp to extract data from the source database.

Oracle ----"Rollback useSql> CREATE table TBL (name VARCHAR2 (10)); Table created. sql> INSERT into TBL values (' Zhiqiao '); 1 row created. Sql> select * from TBL; NAME----------Zhiqiao sql> Delete tbl; 1 row deleted. Sql> select * from TBL; No

Oracle "Recycle Bin" in Oracle 10G by fenng Http://www.DBAnotes.net In Oracle 10G, the concept of a Recycle Bin (recycle Bin) is introduced. The Recycle Bin, in principle, is a data dictionary table, where the user drops the database object

In Oracle 10G, the concept of a Recycle Bin (recycle Bin) is introduced. 　　 The Recycle Bin, in principle, is a data dictionary table, where the user drops the database object information. The object that the user is dropping is not deleted by the

A data dictionary is a collection of metadata, such as created tables, columns, constraints, triggers, and so on, which are metadata that need to be saved in the database. In addition, some of Oracle's own database objects, such as directories,

The before-image in undo is affected by system load and other factors, and its retention time is short. Sometimes it cannot fully meet the flashbackquery, flashbackversionquery, and other flashbacks. The before-image in undo is affected by system

Null indicates an ambiguous or unknown column value.   Test Table: testnull (ID varchar (32 )) Database: Sybase asa11.0 Row data (''), (null)   When the database option ansinull is true (which is also the default option of the ASA database, Select *

Environment: sys@ORCL> select * from v$version where rownum=1;BANNER----------------------------------------------------------------Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Prodsys@ORCL> !uname -aLinux localhost.localdomain 2.6.18-

Funny test of dual table C:/> sqlplus "/As sysdba" SQL * Plus: Release 9.0.1.0.1-production on Thu Aug 8 09:20:57 2002 (C) Copyright 2001 Oracle Corporation. All rights reserved. Connected:Oracle9i Enterprise Edition Release 9.0.1.1.1-ProductionWith

A virtual index is a "false" index, which is defined in a data dictionary, but does not have the corresponding index segment, that is, it does not allocate any storage space. Using Virtual indexes, developersYou do not need to wait for the index to

Why does when sometimes have no values [ID 762738.1] Why does DBA_TAB_MODIFICATIONS sometimes have no values [ID 762738.1] When Modified 18-MAR-2009 Type HOWTO Status MODERATED In this Document Goal Solution References when --------------------------