This document discusses the basics of database management systems (DBMS). It begins by explaining the data storage hierarchy from the bit level up to the database level. It then covers different database models including hierarchical, network, relational, and object-oriented. Key components of a DBMS like DDL, DML, query language, and report generators are defined. Commercial DBMS examples are provided. The document concludes with an overview of creating and using a database, including defining the structure, entering data, and searching for information.

1. DBMS

2. Data Storage HierarchyBit: it is smallest unit of data a single binary Digit.

3. Character: Multiple related bits are combine to form a character(M,8,$..etc).

4. Field: Multiple related character are combine to form field. (employee code, emp name).

5. Record: Multiple related field are combined to form record. (a student record will contain field containing data of the students) Data Storage HierarchyFile: Multiple related file are combine to form a file.(a collection of all employee record of a company will be employee file.)

6. Database: Multiple related file are integrated to form a Database. (multiple employee file such as salary file, Personnel information file, Skill Set file) Database Model A database model defines the manner in which the various files of a database are linked together.

7. The commonly used database model are:Hierarchical Database.Network Database.Relational Database.Object Oriented Database.

8. Hierarchical Database ModelThe data element are linked in form of inverted tree structure.

9. Root at the top.

10. Parent-child relationship

11. Parent data element is one and can have one or more subordinate or child element.

12. There may be many child but only one parent data element.Hierarchical Database ModelThe data element of many applications can be neatly organized with this model

13. The main limitation is, it does not support flexible data access because the data can only be accessed by following the tree structure.

14. Hence the mapping of data and their relationship in tree structure is very important when the database is first design.Network Database Model It is extension of Hierarchical Database model.

15. It follows parent-child relationship.

16. The mapping of data and their relationship is very important when the database is first design.

17. Here the child data can have more than one parent and can have no parent at all.

18. Here the extraction of information can be from any data element in database structure instead of root data element.Relational Database Model Here the data element are organized in form of multiple tables with rows and columns.

19. Each table represents separate file.

20. Each table column are represent as field.

21. Each table row are represent as data record.

22. The data in one table are related to data in another table by common field.Relational Database Model It provide grater flexibility in data organization and future enhancement.

23. If new data is to be added then it is not necessary to redesign the database rather new table can be easily added. Database Model Some Limitation Of Database Models Are:Ability to model complex nested entities such as engineering objects, multimedia documents.Have only a limited set of data types they do not allow storage and retrieval of long unstructured data such as images, audio and textual documents.

24. Object-Oriented DATABASE MODEL It was introduced to overcome the above listed shortcoming.

25. IT is a collection of object whose behavior, state and relationship is defined according to object oriented concept.Object-Oriented DATABASE MODEL

26. Main Components of DBMS: Data Definition Language (DDL).

27. Data Manipulation Language (DML)

28. Query Language

29. Report Generator.Data Definition Language (DDL). IT is use to define the structure of a Database. The database structure definition (Schema) typically includes the following:Defining all data element.

30. Defining data element field and records.

31. Defining the name, field length, and field type for each data type.

32. Defining control for field that can have only selective values.

33. Defining the logical relationship among various data element.

34. Defining access control for security purpose.Data Definition Language (DDL)In short every thing about the database structure is included in its schema.

35. This description can be use by system analyst in defining new application.