Database Administrator

Q: What is NULL? A: When we do not know the specific data, it is also unknown. We can use NULL. We call it NULL. in ORACLE, the column length containing NULL values is zero. ORACLE allows blank fields of any data type, except for the following two

System Requirements: written according to Oracle9I) the following system requirements apply to typical Oracle Installation and creation of simple databases.Memory: the installation of the Oralce 9i software requires at least MB of memory.Swap zone:

There are four types of SQL languages: DQL, DML, DDL, and DCL. It is used to define the data structure, such as creating, modifying, or deleting a database; DCL is used to define the permissions of database users; in this article, I will detail how

Gradually record the creation, content, and meaning of Oracle Data Dictionary tables. It is a process of learning by yourself. You can use it as a record for reference. View_Name Meanings Come from GV $ ENQUEUE_LOCK This

The data types and sizes in database storage vary. In some cases, only the numeric type is stored, and some only the text type is stored. Many databases support various specialized types: Date and Time, binary character, and Boolean. Matching data

For program developers, the two most popular backend databases are MySQL and SQL Server. The most basic similarity between the two is data storage and query system. You can use SQL to access the data of these two databases, because they support ANSI-

Storage Engine Data in MySQL is stored in files (or memory) using different technologies. Each of these technologies uses different storage mechanisms, indexing techniques, locking levels, and ultimately provides a wide range of different features

A version issue occurs when an application is to be distributed to customers, or even multiple locations in the same company. If the program is designed to use specific features of a specific version of Oracle, it will fail to run in earlier

Content directory Project RealIntroductionInteraction with Analysis ServicesDatabase DesignData Source and data resource view Data SourceBest Practice: Remember your password when working in standard security mode. When you move an object, you often

You need to pay extra attention when creating synonyms that contain database links. Otherwise, problems may occur. If the synonym points to the object of the current user, there will be no problem: SQL> CONN YANGTK/YANGTK @ YTK is

Sometimes we encounter such a situation where the existing database needs to be transferred from one machine to another. Generally, we use export and import. However, if the database contains a large amount of data and the size of the data file is

Oracle recovery management RMAN) has many functions that can be used to help back up and restore processes. This tool has command line and GUI versions. Generally, RMAN executes and standardizes the backup and recovery processes, and reduces DBA

Oracle Advanced Replication, also known as symmetric replication. Unlike other Oracle functions, Oracle Advanced Replication is not plug-and-play. Users must have a deep understanding of how it works and the advantages and disadvantages of various

Oracle 8i Database Server is a highly optimizable software product. Regular adjustments can optimize system performance and prevent data bottlenecks. By adjusting the database system, we can achieve optimal performance to meet user needs. Below, I

Developers often use Access as the prototype or use Access to develop applications that are not critical. However, as the company's business grows, the problems to be solved will become more and more complex, and the Access environment may not meet

I. Multi-resident Multiple Residency) means to run Multiple OnLine instances on the same host. Each OnLine instance has and manages its own processes, shared memory, and disk space. Multi-resident does not mean to install OnLine software to multiple

1. First, make the following assumptions about the environment for the following operations: 1. Server SideServer machine name: scoserverip address: 10.0.0.1Database Name: informixserverservicename: sqlexecPort: 5000/tcpDatabase username:

A datetime field can store the date range from the first millisecond of January 1, January 1, 1753 to the last millisecond of January 1, December 31, 9999. If you do not need to cover such a large range of dates and times, you can use SMALLDATETIME

When Microsoft Windows Server 2000 and Oracle8i reading is Edition 8.1.7 are in use, the client application reports a read/write error in the data window view, enters Oracle DBA Studio as SYSDBA, and finds "D: ORACLEORADATAORCLAPINFO. DBF "data file"

1. What is bad database blocks? First, let's take a rough look at the format and structure of the database block-The database data block has a fixed format and structure, divided into three layers of cache layer, transaction layer, data layer. When