Oracle

1, the table's primary key, the foreign key must have the index;2, the data volume of more than 300 of the table should be indexed;3. Tables that are often connected to other tables should be indexed on the connection field;4. Fields that often

--1 Creating a Database--You can use the default ORCL database--or use the database configuration assistant inside the config and porting tool to help create the databases.--2 Creating table Spaces--Temporary table spaceCREATE Temporary tablespace

Oracle Flashback Technologies-Estimating the amount of flash logs generated at different time periodsV$flashback_database_statA statistic that monitors the I/O overhead of the flashback data and estimates the flashback space requirement based on the

System environment:CentOS Release 6.7 (Final)Oracle Database 11g Enterprise Edition Release 11.2.0.4.0-64bitOperation Process:1. When you add a data file or create a tablespace, you specify the path as a single-node localSql> alter tablespace users

Subquery: A subquery When a query statement, he is nested in other SQL statements, the purpose is to provide data for the outer SQL statements, sub-queries can be used in DDL,DML,DQL.Using subqueries in DDL, you can quickly create a query-to-sum

Stored procedures are used to perform specific operations when a stored procedure is established, you can specify either an input parameter (in) or an output parameter (out), you can pass the data to the execution part by using the input parameters

First, create a userOverview: In Oracle, to create a new user using the Create USER statement, you typically have DBA (database administrator) permissions to use.Create user username identified by password;Note: Oracle has a problem, the password

1 sql>-- string case sensitivity 2 sql>-- query the employee named King 3 sql> SELECT * 4 C6/>2 from emp 5 3 where ename = ' KING '; 6 7 sql>-- date format sensitive 8 sql>--Query the entry date is 1 July-November-81 of employees 9 sql> SELECT

NVL (commission_pct,0)If the first argument is null, the second argument is returnedIf the first argument is non-null, the first argument is returnedCOALESCE (EXPR1,EXPR2,EXPR3 ... EXPRn)A non-null value is returned when the first non-null value is

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database system: Microsoft's SQL Server, IBM DB2, Oracle of Oracle, MySQL, etc., are more well-known database management software. Now let's start with the Oracle database.Managing Oracle DatabasesOem:oracle Enterprise ManagerUsing graphical

This article mainly introduces the common operation examples of Oracle tablespace, including creating, querying, adding, deleting, modifying. Table spaces and data files commonly used data dictionaries and dynamic performance views include V$dbfile,

-----------Windows environment-------------------------------------1. Monitor Start & CloseLsnrctl start // prompt Start monitoring successful // Prompt to start monitoring successfully after net stop ORACLESERVICEORCL.2. Check the Listener

Oracle establishes tablespaces and users To establish the tablespace and the user's steps: User Create:Create user username identified by "password"; Authorization:Grant create session to user name; Grant create table to user name;

Purpose: Cloning an Oracle Home, can eliminate multiple machines to repeatedly install Oracle software1. Stop related processes[Email protected] bin]#./crsctl Stop Cluster-all2. Packing Dbhome_1 Catalogue[Email protected] 11.2.0]#

Each database has a Alert_.log file, and the default storage path is $oracle_base/diag/rdbms///trace.A database alert file is a log file that lists messages in chronological order, such as: Any non-default initialization parameters used at

1: After a few days of tossing, and finally Oracle installation success, create users, authorization and so on, then settle down learning Oracle;Install the Plsql GUI and after the Chinese (the process of Baidu, Baidu more and more), login graphical

Backup and restore of voting disk files using the DD command is no longer supported in 12cThe administration of voting files requires OCR files to work properly. Use Ocrcheck to check the status of the OCR file before deleting, adding, replacing, or

1. Set the ID as a self-increment sequenceCREATE OR REPLACE TRIGGER "Datalib". " Trig_user_add "Before INSERT on ' Sys_user ' for each rowBeginSelect Seq_user.nextval into:new. " USER_ID "from dual;EndALTER TRIGGER "Datalib". " Trig_user_add "ENABLE;

I. Oracle basic data type 1, character data type Char: stores a fixed-length string that, if not specified, has a default of 1 bytes, and if the length of the data does not reach the specified length, the space is padded to reach the