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COBOL/FORTRON |
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QUERIES |
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DBMS |
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Operating System |
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Data Base |
A database is a collection of related information stored so that it is available to many users for different purpose. The content of a database is obtained by combining data from the entire different source in an organization. So that data are available to all users and redundant data can be eliminated or at least minimized. A Computer database gives us some electronic filing can be eliminated large number of ways of cross referring and this allows the user many different ways in which to reorganize and retrieve data.
The Three Level Architecture of Database management system
- External level or subschema
- Conceptual level or conceptual schema
- Internal level or physical schema
- Mapping between different levels.
Database management system facilities
Data definition language;
Database management system provide a facility known as the data definition language (DDL), which can be used to define the conceptual schema and also give some details about how important this schema in the physical devices used to store data.
Data Manipulation Language;
DML is a language that enables users to access or manipulate as organized by the appropriate data model. Data manipulation involves retrieval of data from the database, insertion of new data into the database and deletion or modification of exiting data.
Elements Of a database management system;
- DML Precompiler
- DDL compiler
- File manager
- Database manager
- query processor
- Database Administrator
- Data Dictionary
