Oracle management rules and full relational

Database Management System DatabaseManagementSystem (DBMS) is a software used to manage a database. It acts as a knowledge base for all data and is responsible for its storage, security, consistency, concurrent operations, recovery, and access. DBMS has a data dictionary, which is sometimes called a system directory) that stores the data of every thing it owns, such as name, structure, location, and type, this type of data is also called metadata ). The logical and physical information of a piece of data is recorded in the data dictionary. Database System Administrator DatabaseAdministrator, DBA) should be familiar with the DBMS data dictionary; during the entire lifecycle of the database, the data dictionary serves him or her.

DBMS should follow the twelve rules proposed by Codd to be classified into full relational databases:

1) Information rules. Information is expressed as data stored in a unit. As discussed earlier, using VIN as a single column violates this management Oracle rule.

2) authorization access rules. Each data item must be accessed through a combination of "table name + row primary key + column name. For example, if you can use an array or pointer to access a column, it violates this Oracle management rule.

3) null values must be used in a consistent manner. If the numeric value is missing and the Null value is treated as 0, or the character value is treated as a space, it violates this Oracle management rule. A null value only indicates that data is missing and no value exists. If the missing data requires a value, the software provider generally provides the ability to use the default value for this purpose.

4) an active online data dictionary should be stored as a relational table, and the dictionary should be accessible through conventional data access languages. If any part of the data dictionary is stored in an operating system file, it violates this Oracle management rule.

5) Apart from possible low-level access routines, the data access language must provide all the access methods and be the only way to access them. If you can use a utility instead of an SQL interface to access a file that supports a table, it may violate this Oracle management rule. See manage Oracle management rules 12.

6) All views that can be updated should be updatable. For example, if you can link three tables as the basis of a view, but cannot update this view, it violates the management rules of this Oracle database.

7) Set-level insertion, update, and deletion are required. At present, most RDBMS providers provide this capability to some extent.

8) Independence of physical data. The application cannot rely on the physical structure. If a file supporting a table is moved from one disk to another or renamed, the application should not be affected.

9) Independence of Logical Data. Applications should not rely on logical structures. If a table must be divided into two parts, a view should be provided to connect the two parts so as not to affect the application.

10) Integrity independence. Integrity Management Oracle management rules should be stored in the data dictionary. Primary Key constraints, foreign key constraints, check constraints, triggers, and so on should all be stored in the data dictionary.

11) distribution independence. A database should continue to work even if it is distributed. This is an extension for managing Oracle management rule 8. A database can be distributed not only locally in a system, but also remotely through the system network.

12) Non-Destructive law. If low-level access is allowed, security or integrity management rules cannot be bypassed. These Oracle management rules are observed by conventional data access languages. For example, A backup or loading tool cannot back up or load data without verification, constraints, and locks. However, software vendors generally provide these features for speed reasons. Then, the database system administrator has the responsibility to ensure data security and integrity. In case of instant problems, it should be immediately restored. For example, when loading VLDB, You can temporarily disable and re-enable the constraints check. If a DBMS meets all the basic principles discussed in this chapter, two definitions, six attributes, relational operations, and two integrity management Oracle management rules, and these twelve rules, then it can be treated as an RDBMS.

Codd summed it up with his rule: "for a system that is qualified to become an RDBMS, the system must exclusively use its relational tools to manage databases ."

1. Manually set Oracle management control and log files
2. Create a data dictionary using an Oracle management script
3. Oracle management tool-Overview of Oracle SQL Handler Functions
4. From Code Officers to Oracle Administrators
5. Oracle Management System Overview: features, subsystems and modules