Class: BCASY(Sem IV) COCSIT, Latur Sub: Data Structure and algorithm
BCA – 402 DATA STRUCTURE and ALGORITHM
1. Introduction and Overview
1.2 Basic Terminology; Elementary data organization:-
(a) Data.
(b) Data item.
i) Group item.
ii) Elementary data item.
(c) Organization of data.
i) Attribute
ii) Entity
iii) Entity set.
(d) Information.
i) Field
ii) Record
iii) File
(e) Primary key.
(f) Classification of record.
i) Variable length
ii) Fixed length.
(a) Data :- Data are simply value or set of value.
Ex.: “LATUR”, 8.
(b) Data item :- Data item is single unit of values.
Ex.: “LTUR”,67.
Further data item are get divided into two parts.
i) Group items
ii) Elementary items.
i) Group items :- Data items that are divided into subitems are called
group items.
By: Saudagar Asif
,Class: BCASY(Sem IV) COCSIT, Latur Sub: Data Structure and algorithm
Ex.: Employee Name : More Ram Hari
Employee name get divided into three subitems as first name, middle
name and last name.
ii) Elementary items :- Data items that are not divided into subitems
are called elementary item.
Ex.: 14 – 03 – 2022.
Social security number is treated as a single item.
(c) Organization of data :-
Collection of data are frequently organized into hierarchy of fields,
records and files.
- The above concept can be more cleared using following additional
terminology i.e. attribute, entity and entity set.
i) Attribute :- A attribute is a specified memory area used to store
data.
ii) Entity :- A entity is something that has retain attributes or
properties which may be assigned values. Here assigned values may
be either numeric or non-numeric.
Ex.: Attributes: Roll No. Name Grade
Values: 01 Ajay A
iii) Entity Set :- Entities with similar attributes form an entity set.
Each attribute of an entity set as a range of values, the set of all
possible values that could be assigned to the particular attribute.
Ex.: All the employees in an organization.
(d) Information :- A meaningful or processed data at particular attribute is
called as “information”.
The way that data are organized into the hierarchy of fields, records and
files, shows the relationship between attributes, entities and entity set as:
i) Field :- A field is a single elementary unit of information
representing an attribute of an entity.
By: Saudagar Asif
, Class: BCASY(Sem IV) COCSIT, Latur Sub: Data Structure and algorithm
ii) Record :- A record is the collection of field values of a given entity.
iii) File :- A file is the collection of records of the entities in a given
entity set.
(e) Primary key :- Every record in a file may contain many field items, but
the value in certain field may determine the record in the file uniquely.
Such a field K is called a primary key, and the values K1, K2, K3, …. Kn in such
a field are called key values or keys.
(f) Classification of Records :-
Records may also be classified according to the length.
A file can have fixed-length records or variable-length record.
-In fixed-length records, all the records contain the same data items
with the same amount of space assigned to each data item.
-In variable length records, file records may contain different lengths.
Ex.: Student records usually have variable lengths, since different
student take different number of courses.
Usually variable length records have a minimum and a maximum
length.
1.3 Data Structures :-
The logical or mathematical model of a particular
organization of a data is called a data structure.
The choice of a particular data model depends on two considerations:
i.The data model must be large in structure to show the actual
relationship of the data in the real world.
ii.The structure should be simple enough that one can effectively
process the data when necessary.
Following figure shows types of data structures:
By: Saudagar Asif
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