Database management systems

1. Database management systems

2. Data and information • Data are raw, unorganized facts that need to be processed. Data can be something simple and seemingly random and useless until it is organized. For example, student's test score is one piece of data. • When data is processed, organized, structured or presented in a given context so as to make it useful, it is called information. For example ,The average score of a class or of the entire school is information that can be derived from the given data.

3. Data Hierarchy Data Hierarchy refers to the systematic organization of data, often in a hierarchical form. Data organization involves fields, records, files and so on. • BIT :All data is stored in a computer's memory or storage devices in the form of binary digits or bits. A bit can be either 'ON' of 'OFF' representing 1 or 0. • BYTE: is a group of 8 bits. One byte can represent one character or, in different contexts, other data such as a sound, part of a picture etc. • FIELD: is a group of characters. e.g. data held about a person may be split into many fields including ID Number, Surname, Initials, Title, Street, Town, etc • RECORD: is a group of fields holding all the information about one person or item. • FILE: a collection of records. A stock file will contain a record for each item of stock, and so on. • DATABASE: may consist of many different files, linked in such a way that information can be retrieved from several files at once

5. Maintaining data Data change from time to time. Historic data may mot change but recent data may change hence there is the need to maintain the integrity of data using computerized methods. Database management systems are used to maintain data in order to preserve its integrity. Database Maintenance is a term we use to describe a set of tasks that are all run with the intention to improve your database. There are routines meant to help performance, free up disk space, check for data errors, check for hardware faults and update internal statistics.

6. File Processing Traditional file processing systems include manual systems and also computer based file systems that were linked to particular application programs. This is the type of file processing that you used with programming languages.

7. Characteristics of File Processing Systems The focus is on the individual processing needs of a particular department or area within an organization. These may be, for example, Accounts Receivable, Payroll, or Inventory Control. Each application is designed with its own set of data files. The data may already be present in files for other applications but would need to be restructured to meet the needs of the new application

8. Database Management System (DBMS) A database management system (DBMS) is system software for creating and managing databases. The DBMS provides users and programmers with a systematic way to create, retrieve, update and manage data. A DBMS makes it possible for end users to create, read, update and delete data in a database. The DBMS essentially serves as an interface between the database and end users or application programs, ensuring that data is consistently organized and remains easily accessible.

10. Advantages of using a DBMS • Controlling data redundancy • Restricting Unauthorized Access • Providing persistent storage of data • Providing storage structures and search techniques for efficient query processing • Providing backup and recovery • Providing Multiple User Interfaces • It promotes data integrity

11. Relational Database Management Systems A relational database management system (RDBMS or just RDB) is a common type of database whose data is stored in tables. Businesses these days are relational databases, as opposed to a flat file. Relational databases are used to handle multitudes of data and complex queries, whereas a flat file takes up more space and memory, and is less efficient. The databases use multiple tables as standard. The data is stored in lots and lots of tables, or ‘relations’. These tables are divided into rows (records) and columns (fields).

13. Object Oriented Database management Systems An object-oriented database management system (OODBMS) is a database management system that supports the creation and modeling of data as objects. OODBMS also includes support for classes of objects and the inheritance of class properties, and incorporates methods, subclasses and their objects

15. Web database A Web database is a database application designed to be managed and accessed through the Internet. Website operators can manage this collection of data and present analytical results based on the data in the Web database application. Databases first appeared in the 1990s, and have been an asset for businesses, allowing the collection of seemingly infinite amounts of data from infinite amounts of customers.

16. Database Administration Database administration refers to the whole set of activities performed by a database administrator to ensure that a database is always available as needed. Database administration enables you to help companies create new or update existing databases based on their internal data collection needs.

17. Functions of a database administrator • Authorize access to the database. • Coordinate and monitor users of the database. • Acquire software and hardware resources as needed. • Takes care of the security of the database. • Takes care of the system response time.