l8 components and properties of dbms

Components of DBMSProperties of DBMS

Version 1.1

Rushdi Shams, Dept of CSE, KUET 1

File Processing System


CheckingAccountPrograms

AutoLoan

Programs

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Database Processing System


DatabaseManagementSystem

CheckingAccountPrograms

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Programs SavingsAccountPrograms

Database

How DBMS Works


SQL PLUS

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ORACLE DBMS

Plan-> Runs-> Compiles ->Result set

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How DBMS Works


JAVA Code

{

String( “select…”);

}

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ORACLE DBMS

Plan-> Runs-> Compiles ->Result set

JDBC

Components of DBMS

1. Models Hierarchical model Network model and Relational model


Components of DBMS (continued)

2. Data structuresThis defines the properties of several aspects of rows/records and columns/fields, etc



3. A query languageallow users to interactively interrogate the database, analyse its data and update it according to the user privileges on data

so, you can say query language actually provides

Analysis on data Interrogation on data Security on data



4. Transaction MechanismTransaction means data moving between two or more databases. It provides ACID property.

In case of database systems, ACID stands for Atomicity Consistency Isolation and Durability



AtomicityIt is the ability of the DBMS that ensures either all of the transactions take place or none of them take place!Kind of weird, huh? Well, let me give an example. If a bank account is debited, another bank account must be credited- that is called atomicity!



ConsistencyEvery database has some rules according to the organization to which it belongs. This property ensures that the databases are in legal state after a transaction takes place.For example, if a bank says that its client’s account balance can never be negative, then no such transaction will take place that makes a balance negative.



IsolationThis property ensures that no other operation can intervene the transaction operation.For example, a bank manager, during a transaction should be able to see balance of one account, not on both.

This is the most relaxed option in ACID properties.



DurabilityThis property ensures that once a transaction takes place, it cannot be undone.

when an account to account transfer takes place, after completion, it should notify the user that transaction successfully done and you cannot rewind that!


Properties of Database Data Sharing Data Integration Data Security Data Abstraction Data Independence


Data Sharing Do you think records are kept to be used by

only one person? Or, should it be shared, so that we can use it?


Data Integration This implies that a database should be a

collection of data which, at least ideally, has no redundant data.

Redundant data is unnecessarily duplicated data.

A data value is redundant when an attribute has two or more identical values.

A data value is redundant if you can delete it without information being lost.


Data Integrity The database should accurately reflect the

universe of discourse that it is attempting to model.

if relationships exist in the real world between objects represented by data in a database then changes made to one partner in such a relationship should be accurately reflected in changes made to other partners in that relationship


Data Security One of the major ways of ensuring the

integrity of a database is by restricting access – in other words, securing the database.

Define a set of authorised users of the whole, or more usually parts, of the database.


Data Abstraction An academic database is meant to record

relevant details of university activity. We say relevant, because no database can store all the properties of real-world objects. A database is therefore an abstraction of the real world


Data Independence If a change is made to some part of the

underlying database, no application programs using affected data should need to be changed.

Also, if a change is made to some part of an application system then this should not affect the structure of the underlying data used by the application.


l8 components and properties of dbms

Technology

data rushdi shams

dept of cse

redundant data

data integrity

data value

data interrogation

affected data

duplicated data