Oracle

A view is a logical table based on one or more tables or views. It does not contain data and allows you to query and modify the data in the table. A view-based table is called a base table, which is an Oracle database.There are five types of objects:

The database was installed yesterday and can be used after the installation is complete. It cannot be used after it is started today, prompting Oracle not available. Later, I searched for information. It is said that the Oracle service was not

Http://www.cnblogs.com/wenlg/archive/2010/05/19/1738893.html     Oracle Database 10g Release 2 (10.2.0.1.0) Enterprise/Standard Edition for Microsoft Windows (32-bit)

Because the Oracle service occupies a large amount of resources, it is recommended that you do not need to check it if it is not used at ordinary times. If you need to activate the service again, you can disable it and change other services to

The grouping function acts on a group of data and returns a value for a group of data. Group function type AVG average count returns the total number of records not empty Max maximum Min SQL> select AVG (salary), max (salary), min (salary), sum

Http://wanwentao.blog.51cto.com/2406488/457603 Create and modify users Create userStatement to create a user. When a user connects to the Oracle database, it must be verified. There are three types of authentication in

Normally, after the SELECT statement, create index, and other sorting operations using the temp tablespace are completed, Oracle Automatically releases the temporary segment. However, if some temporary segments are not released, the temp tablespace

Recently, due to work needs, we need to optimize the current program. Considering a version in each region, the maintenance cost is too high and the difficulty is too high, it is decided to encapsulate codes of different regions and businesses using

We know that Oracle uses data dictionaries to manage and display database information, which is crucial.Correct understanding of this part helps to enhance our Oracle learning capabilities. Next we will introduce how to study the database through

Oracle claims that the installation of the Oracle9i database in Linux requires at least MB of memory and at least 1 GB or two times of memory swap space. For servers with a system memory larger than 2 GB, the swap space can be between 2 gb-4gb. If

I. B-tree indexes 0. B-tree indexes do not have non-unique entries. 1) in a non-unique index, oracle adds rowid as an additional column to the key to make the key unique. Exp: Create index I on T (x, y). In terms of concept, create unique index I on

I. Introduction: the most important part of database adjustment is to rewrite the SQL code with poor running efficiency. The SQL code after rewriting may be significantly different from the previous one in terms of running efficiency! However, when

1. Oracle database character set (NLS) is used to store, process, and retrieve data in their own languages and formats. With global support, Oracle provides users with familiar database mother-tongue environments, such as date formats, digital

  Batch Processing is generally used in ETL operations. ETL stands for extract, transform, and load. It is the word of a data warehouse! Similar to the following structure:For X (select * from ...) Loop Process data; Insert into table values

  Oracle supports returning the result set after calling the stored procedure through the ref cursor. Using the cursor is much better than returning array variables in terms of memory consumption and time! Example: Create a package for the

  To enable the Oracle client to normally connect to the Oracle server with a firewall, it is not enough to open a 1521 or custom listening port. To test Bom's multi-tier to single-tier programs last night, you need to connect to Oracle on the

  1. Input. CTL Load dataInfile '/u1/out/cxcq201/test.csv' -- specify the path here, if not running in the same directoryReplace into Table tc_ccj_fileFields terminated by "," optionally enclosed '"'Trailing

I. There are two types of auto-increment self-segments for tables. One is that different tables use their respective sequence. The method is as follows:1. Create a sequence in Oracle sequence first Create sequence seq_idminvalue 1 start with 1

A bunch of problems after installation. The first step is that the logon fails and the password and user name are unknown.   So I used database configuration and migration tools to create a database demo. At the time of creation, I gave AAA

Select TCP/IP (Internet Protocol) and click Next, as shown in:     Figure (6) Enter the host name and port number. Note that the host name and port number must be the same as the host name and port number configured by the listener on the database