Introduction to
database management system
What is data , relationship, constraints and schema?
- Data is a collection of facts and also it is defined as binary computer representation of logical entities.
- Relationship is the association between the various data elements.
- Constraints are predicates that define the correct database states.
- Schema describes the organization of data and relationship within the database.
What is a database?
Database is a collection of data designed to be used by different people is called a database.
And the data is maintained with inter relationships with controlled redundancy to serve one or more applications
What is database management system?
Database management system is a collection of programs that enables you to store , modify and extract information from a database.
The services provided by the database management system are
Explain DML and DDL statements.
Data definition language is used to define and manage all attributes and properties of a database.
Most DDL statements include following commands
CREATE
ALTER
DROP
Data Manipulation Language
Data manipulation language is used to select, insert, update, and delete data in the objects defined with DDL.
Transaction management
a transaction is a sequence of database operations that represents a logical unit or words and that access the database and transforms it form one state to another state
a transaction can update, delete, modify a set of records
Concurrency control
it is the method of controlling the database manipulation processes that are running simultaneously that access shared data
Recovery management
recovering the trasaction to its previous state if any failure or abortion occurs while doing a transaction
Security management
security management means protecting the data from unauthorized access
Language interface
the interface which is provided by the database management system to do data manipulation without worrying about the physical implementation
storage management
the dbms allows us to store the data in the secondary storage devices by interacting with the operating system.
Explain the types of database management system?
Hierarchical
The hierarchical data model organizes data in a tree structure. There is a hierarchy of parent and child data segments. In this type of structure .
This model organizes the data elements as tabular rows one for each instance of an entity.
Advantages: simplicity, Data security, Data integrity.
Disadvantage: Implementation complexity, database management problems, programming complexity
Network Model
The network model handles the many to many relationships. It allows records to have more than one parent. In this a set is made of at least two types of records owner record, and member record
Relational Model
A database based on the relational model developed by E.F. Codd. A relational database allows the definition of data structures, storage and retrieval operations and integrity constraints.
The data and relations between them are organized in tables.
A table is a collection of records and each record in a table contains the same fields.
Object oriented Model
Object DBMSs add database functionality to object programming languages.
Object DBMSs extend the semantics of the C++, Smalltalk and Java object programming languages to provide full-featured database programming capability
Here entity is represented as a class . a class represents both object attributes as well as their behaviors of the entity
This model is well suited for multimedia applications.
Object relational model
This model combines the features of both object oriented and relational model making it more powerful yet to manage the data elements in the database.
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