ENTITIES:
- Entities are the basic units used in modelling stones
of concrete or abstract objects. All such items about which relevant
information is stored in the database are called ENTITIES. ENTITY is the
identical objects which are transformed from manual to computer system. E.g. Building, room, chair, transaction, course,
machine, employee.
ATTRIBUTES:
- The qualities of the entity which we store as information are called the
attributes. OR The properties that characterize an entity set are called as
attributes. It is also referred as data item, data element, data field, items, elementary
item or object property.
DOMAIN: - Each attribute of an entity set has a particular value. The set of possible values that a given attribute can have is called its DOMAIN. Eg. The set of value that the attribute EMPLOYEE. Salary may have take is a positive number ranging between 0.00 and 9,999,999.00.
ENTITY
SET ATTRIBUTES VALUE
EMPLOYEE EMPLOYEE.soc_sec_no 1254
EMPOYEE.Name Amitesh
EMPLOYEE.
Address Patna
EMPLOYEE.Desgnation System
admin
EMPLOYEE.
Skill DBA
EMPLOYEE.
Salary 45056.00
