database

application program:

a computer program that interacts with database by issuing an appropriate request (SQL statement) to the DBMS

system catalog (metadata) provides

description of data to enable program-data independence.

database management system

A software system that enables users to define, create, maintain, and control access to the database

File-Based Systems

Collection of application programs that perform services for the end users (e.g. reports).

software

DBMS, opearting systeM, network software and also the application programs

Database Approach arose because

Definition of data was embedded in application programs, rather than being stored separately and independently. No control over access and manipulation of data beyond that imposed by application program

seperation and isolation of data

Users of one program may be unaware of potentially useful data held by other programs.

duplication of data

Wasted space and potentially different values and/or different formats for the same item

A database is

an organized collection of data.

hardware

can range from a pc to a network of compters

programming: structure query language - functions

comparison, computation

data control language

controlling access to database for security and integrity commands: GRANT REVOKE

logically related data compromises

entities, attributes, and relationships of an organization's information

data dependence

file structure is defined in the program code

data manipulation language

general enquiry facility of the data commands: SELECT, UPDATE, INSERT, DELETE

programming: structure query: data level

insert, delete, update

procedures

instructions and rules that should be applied to the design and use of the database DBMS

incompatible file formats

programs are written in different languages

fixed queries/ proliferation of application programs

programs are written to satisfy particular functions

Limitations of File-Based Approach

seperation and isolation of data duplication of data data dependence incompatible file formats fixed queries/proliferation of application programs

database

shared collection of logically related data, designed to meet the information needs of an organization

Result:

the database server database management system

data

used by the organization and a description of this data called the schema

programming: structure query second benefit

user and data access control

What are the processes that database carries out

• Data storage • Data access • Data relationship • Data and user management

Data definition language (ddl)

• Define tables, data types, structures and data constraints. commands: CREATE, ALTER, DROP