DATABASE MANAGEMENT SYSTEM
DBMS uses the internet services to
communicate reports, queries and distribute
other information throughout the accounting
system. The process of computerized accounting
system uses databases to store and retrieve data
in the form of inter-related data tables.
• The first wave consisted of network, hierarchical, inverted list, and (in the 1990’s)
object-oriented DBMSs; it took place from roughly 1960 to 1999.
• The relational wave introduced all of the SQL products (and a few non-SQL)
around 1990 and began to lose users around 2008.
• The decision support wave introduced Online Analytical Processing (OLAP) and
specialized DBMSs around 1990, and is still in full force today.
• The graph wave began with The Semantic Web stack from the Worldwide Web
Consortium in 1999, with property graphs appearing around 2008
• The NoSQL wave includes big data and much more; it began in 2008.
A File Management system is a DBMS that allows access to single files or tables
at a time. In a File System, data is directly stored in set of files. It contains flat
files that have no relation to other files (when only one table is stored in single
file, then this file is known as flat file).
An Entity-Relationship Model represents the
structure of the database with the help of a
diagram. ER Modelling is a systematic process to
design a database as it would require you to
analyze all data requirements before
implementing your database.
BASIC CONCEPT OF ERM
Q-What is entity?
A-An entity in DBMS (Database management System) is a real-world thing or a real-world
object which is distinguishable from other objects in the real world. For example, a car is an
entity. An attribute of an entity gives us information about the characteristic features of an
Tangible Entity : Entities that exist in the real world physically. Example: Person, car, etc.
Intangible Entity : Entities that exist only logically and have no physical existence.
Example: Bank Account, etc.
An entity set is a logical container for instances of an entity type and instances of
any type derived from that entity type.
An entity key is a property or a set of properties of an entity type that are used to
Types of Attributes in DBMS
There are different types of attributes in DBMS:
Single Valued attributes
RELATION IN DBMS
Database relationships are associations between tables that are created using join
statements to retrieve data. The following table describes the database relationships.
Both tables can have only one record on each side of the relationship. Each primary key
value relates to none or only one record in the related table.
A relationship set is a set of relationships of the same type. Formally it is a
mathematical relation on (possibly non-distinct) sets. where is a relationship. For
example, consider the two entity sets customer and account.
There are three different types of degree of relationships, they are as follows −
• Unary relationship
• Binary relationship
• Ternary relationship
TYPES OF RELATIONSHIP
One to One relationship
One to many or many to one relationship
Many to many relationships
cardinality usually represents the relationship between the data in two different tables
tables by highlighting how many times a specific entity occurs in comparison to
another. For example, the database of an auto repair shop may show that a mechanic
works with multiple customers every day.
Relational Data Model
A relational data model involves the use of data
tables that collect groups of elements into relations.
These models work based on the idea that each
table setup will include a primary key or identifier.
Other tables use that identifier to provide
"relational" data links and results. Database
administrators use something called Structured
Query Language (SQL) to retrieve data elements
from a relational database.
There are three stages of data modeling: conceptual, logical, and physical.
Conceptual data models focus on the general structure of the system, the entities
to be included, the business requirements of the database to be built, and the
types of data to be stored.
THREE SCHEMA COMPONENTS
Three-schema architecture is an idea in relational database design that breaks a
database down into three different categories according to its use and structure,
and to the roles played by system administrators, designers and end users.