Data Base Management System
Fie lFile Organization Terms & Conceptscomprises a record; A computer system organizes data in a hierarchy t
A computer system organizes data in a hierarchy that starts with bits and bytes and progresses to fields, records, files, and databases. * A bit represents the smallest unit of data a computer can handle.
* A group of bits, called a byte, represents a single character, which can be a letter, a number, or another symbol.
* A grouping of characters into a word, a group of words, or a complete number (such as a person’s name or age) is called a field.
* A group of related fields, such as the student’s name, the course taken, the date, and the grade, comprises a record.
* A group of records of the same type is called a file.
* A group of related files makes up a database.
* A record describes an entity.
* An entity is a person, place, thing, or event on which we maintain information.
* An order is a typical entity in a sales order file, which maintains information on a firm’s sales orders.
* Each characteristic or quality describing a particular entity is called an attribute. * For example, order number, order date, order amount, item number, and item quantity would each be an attribute of the entity order.
* Every record in a file should contain at least one field that uniquely identifies instances of that record so that the record can be retrieved, updated, or sorted.
* This identifier field is called a key field r, which can be a letter, a number, or another symbol.
A grou
The Data Hierarchy
Entities and Attributesing ers into a word, a group of words, or a complete number (such as a person’s name or age) is called a field. Levels of Abstraction * Physical level: describes how a record (e.g., customer) is stored. * Logical level:
A computer system organizes data in a hierarchy that starts with bits and bytes and progresses to fields, records, files, and databases. * A bit represents the smallest unit of data a computer can handle.
* A group of bits, called a byte, represents a single character, which can be a letter, a number, or another symbol.
* A grouping of characters into a word, a group of words, or a complete number (such as a person’s name or age) is called a field.
* A group of related fields, such as the student’s name, the course taken, the date, and the grade, comprises a record.
* A group of records of the same type is called a file.
* A group of related files makes up a database.
* A record describes an entity.
* An entity is a person, place, thing, or event on which we maintain information.
* An order is a typical entity in a sales order file, which maintains information on a firm’s sales orders.
* Each characteristic or quality describing a particular entity is called an attribute. * For example, order number, order date, order amount, item number, and item quantity would each be an attribute of the entity order.
* Every record in a file should contain at least one field that uniquely identifies instances of that record so that the record can be retrieved, updated, or sorted.
* This identifier field is called a key field r, which can be a letter, a number, or another symbol.
A grou
The Data Hierarchy
Entities and Attributesing ers into a word, a group of words, or a complete number (such as a person’s name or age) is called a field. Levels of Abstraction * Physical level: describes how a record (e.g., customer) is stored. * Logical level:
Bibliography: * Management Information Systems-Laudon and Laudon * Management Information System-L.M.Prasad * Management information system by D P Goyal * Internet Sources-wikipedia and others