The role of oracle database: 1. Oracle can organize, store and manage data according to the data structure; 2. Oracle can be suitable for relational database management of large, medium and micro computers.
The operating environment of this tutorial: Windows 10 system, Oracle 11g version, Dell G3 computer.
Strictly speaking, a database is a "warehouse that organizes, stores and manages data according to the data structure." In the daily work of economic management, it is often necessary to put certain relevant data into such a "warehouse" and process it accordingly according to management needs. For example, the personnel department of an enterprise or public institution often stores the basic information of its employees (employee number, name, age, gender, place of origin, salary, resume, etc.) in a table. This table can be regarded as a database .
With this "data warehouse", we can query the basic situation of an employee at any time as needed, and we can also query the number of employees whose wages are within a certain range, etc. If all these tasks can be automatically performed on computers, then our personnel management can reach an extremely high level.
In addition, many such "databases" also need to be established in financial management, warehouse management, and production management, so that computers can be used to realize automated management of finance, warehouse, and production.
ORACLE is a relational database management system suitable for large, medium and microcomputers. It uses SQL (Structured guery language) as its database language.
SQL mainly includes three functions: data definition, data manipulation (including query) and data control. SQL is a language with a high degree of non-proceduralization. Users only need to explain "what to do" without specifying "how to do it". The language is simple, easy to use and powerful. It integrates online interaction and embedding, and can adapt to a wide range of use environments. . The ORACLE database consists of three types of files: database files, log files and control files.
The data dictionary is a set of tables automatically created and updated by ORACLE. These tables record the user's name, description tables and views, and information about user permissions. The data dictionary is read-only and only queries are allowed. That is to say, the data dictionary is a database resource. Every user can access the data dictionary. The DBA can use the data dictionary to monitor the use of ORACLERDBMS and help users complete their applications. ORACLE RDBMS itself also uses database dictionaries to manage and control the entire database.
When mentioning databases, the first company that comes to mind is usually Oracle. The company was founded in 1977 as a company specializing in database development.
Oracle has always been a leader in the database field. In 1984, the relational database was first moved to desktop computers. Then, Oracle's next version, version 5, took the lead in introducing new concepts such as distributed databases and client/server structures. Oracle's version 6 pioneered row locking mode and support for symmetric multi-processing computers...The latest Oracle8 mainly adds object technology and becomes a relational-object database system. At present, ORACLE products cover dozens of models of large, medium and small computers, and the Oracle database has become one of the most widely used relational data systems in the world.
Recommended tutorial: "Oracle Tutorial"
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