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Lect_2_dbms_its_rnvironment_and_components
- 1. Lecture 2 Database System (INFT-4006)
- 2. Database “A shared collection of logically related data and its description, designed to meet the information needs of an organization”
- 3. Database • Database is collection of information managed by Database management system • It is a single large collection (repository) of data shared among users • All data items are integrated with minimum duplication • Database is shared corporate resource • Database not only contains operational
- 4. Database • The self describing nature of database provides “program-data independence” • The definition of data is separated from the application program • The structure of data is not affected by the program and vice versa • If new data structures are added or existing data structures are modified, they do not affect the application program (if program does not directly depend on what has been modified)
- 6. What is meant by logically related?
- 7. • When we design a database we identity entities, attributes and relationships between these entities An Attribute is a property that describe some aspect of entity that we wish to record A relationship is an association between entitles An Entity s distinct object that is to be represented in database
- 8. • When we design a database we identity entities, attributes and relationships between these entities An Attribute is a property that describe some aspect of entity that we wish to record A relationship is an association between entitles An Entity s distinct object that is to be represented in database
- 9. • When we design a database we identity entities, attributes and relationships between these entities An Attribute is a property that describe some aspect of entity that we wish to record A relationship is an association between entitles An Entity s distinct object that is to be represented in database
- 10. Database Management System • A software system that enables users to define, create, maintain, and control access to the database is called DBMS • DBMS provides user the facility: – To define database through DDL (Data definition Language) – To allow users to insert, update, delete and retrieve data from the database through DML (Data manipulation language) – These facilities are provided through query languages – Most common query language is “SQL”
- 11. (Database) Application Programs • A computer program that interacts with the database by issuing an appropriate request to DBMS is call Application Program • Users interact with database through Application program • Application programs are written in high level programming languages or higher level programming languages (fourth generation languages e.g. SQL)
- 13. Data Entry and Reports Data Entry and Reports DBMS Registration Database Exa m Fe e Fee application program Exam application program
- 14. Views • DBMS provide a View Mechanism to allow each user to have his or her own view of the database • Views have several benefits like: – View can be set up to exclude data that some users should not see – View provides mechanism to customize – View provides an unchanging picture of the structure of the database even if the underlying database structure is changes
- 16. Hardware • The hardware refers to the physical parts of the computer and It also includes various storage devices like hard disks and input-output devices like monitors, printers etc. • Hardware is the most visible part of any information system: the equipment such as computers, scanners and printers that are used to capture data, transform it and present it to the user as output. • The hardware is the actual computer system used for keeping and accessing the database. • Servers have large data storage capacities enabling users to share files and
- 17. Hardware • Workstations, which provide high-level performance for individual users in computationally intensive fields such as engineering. • Databases run on a range of machines from microcomputers to mainframes. This also provides the interface between computers and real-world systems. • When we run Oracle or MySQL on our personal computer, then our computer’s hard disk, our keyboard with which we type in all the commands, our computers RAM, and ROM all become a part of the DBMS hardware.
- 18. Software • The main component of a Database management system is the software. • Software is a collection or set of programs or instructions that tell a computer what to do. The software comprises the entire set of programs, procedures, and routines associated with the operation of a computer system. A set of instructions that directs a computer’s hardware to perform a task is called a program, or software program. • It also includes the database software, operating system, network software used to share the data with other users, and the applications used to access the data.
- 19. Software • This software component is capable of understanding the Database Access Language and converting it into actual database commands to execute or run them on the database. • This is the main component, as this is the program which controls everything. The DBMS software is more like a wrapper around the physical database, which provides us with an easy-to-use interface to store, access and update data. • Some DBMS software examples include MySQL, PostgreSQL, Microsoft Access, SQL Server, FileMaker, Oracle, RDBMS, dBASE, Clipper, and FoxPro
- 20. Data • The word data covers the collection of facts stored in the database. Because data are the raw material from which information is generated • Data stored in the database includes structure data, non-structural data, and logical data. • Structured data is highly specific and is stored in a predefined format, whereas unstructured data is a conglomeration of many varied types of data that are stored in their native formats. This means that structured data takes advantage of schema- on-write and unstructured data employs schema-on-read. • Using a DBMS the database is first constructed, created or defined. After that,
- 21. Data • The primary reason behind the introduction of the database management system is to store and maintain the data within the database • It is the most important component of the database management system. The typical database contains both the metadata(data about data) and the actual(operational) data. • For example – when I store my name in a database, the DBMS will store when the name was stored in database, what is the size of the name, is it stored as related data to some other data?, or is it independent?, all this information is Metadata.
- 22. Procedure • Procedures refer to general instructions to use a database management system. This includes procedures to set up and install a DBMS, To login and logout of DBMS software, manage databases, take backups, generate reports etc. • Procedures can be used for data validation, access control, or to reduce network traffic between clients and the DBMS servers. Extensive and complex business logic can be embedded into the subroutine, thereby offering better performance. •
- 23. Procedure • The basic purpose of the procedures is to help guide users in the operation and management of database systems. • Database Procedures are similar to Database Functions. The major difference is the way in which they are invoked – Database Functions can be used in the same way as for any other expression within SQL statements, whereas Database Procedures must be invoked using the CALL or EXEC statement, depending on the DBMS. • In Enterprise Architect, Database Procedures can be modelled in one of two ways:
- 24. People • People perform different roles in database environment – Data Administrator – Database Administrator – Database Designer – Application Developer – End Users
- 25. Any Question?