Data Resource Management
Fundamental Data Concepts
• Character: single alphabetic, numeric or other symbol
• Field or data item: a grouping of related characters
– Represents an attribute (a characteristic or quality) of some entity (object,
person, place or event)
• Record: grouping of all the fields used to describe the attributes of an entity
• File or table: a group of related records
• Database: an integrated collection of logically related data elements
Database Structures (1.Hierarchical, 2.Network, 3.Relational, 4.Object-oriented )
• Hierarchical: one-to-many Relationships, since each data element is related to only
one element above it.
• Network: Many-to-many relationships
• Relational
• Object-oriented
Relational Structure
• Most widely used structure
• Data elements are viewed as being stored in tables
• Row represents record
• Column represents field
• Can relate data in one file with data in another file if both files share a common data
element
• Relational Structure advantages:
• Easily respond to ad hoc requests
• Easier to work with and maintain
Object-oriented Structure: Encapsulate (combine) data and their operations in one objects.
• Object consists of (data and Operations)
– Data values describing the attributes of an entity
– Operations that can be performed on the data
Data Planning and Modeling
• Enterprise Model (Data Planning): Defines basic business process of the enterprise
– Defined by DBAs and designers with end users
• Data Modeling: A process of identifying and defining the relationships between data
elements by Developing ERD
– The Entity Relationship Diagram (ERD): is simply graphical model of the
various files and their relationships, contained within a database system.
– There are three modeling levels: (conceptual, logical, physical)
• Conceptual model: identifies the highest-level relationships between
the different entities.
• Logical model :describes the details of our data without regard to how
they will actually implemented in the database.
• Physical model describes how to implement our data model in the
database.
Database Management System (DBMS)
• DBMS is main software tool serves as interface between users and databases to help
users easily access the data in a database.
• Examples of popular microcomputer versions of DBMS are Microsoft Access
• Examples of popular mainframe and server versions of DBMS are Oracle , MySQL,
DBMS Major Functions
• Database Interrogation
• Database Maintainence
• Database Development
• Database application development
Database Interrogation: to retrieve and display information selectively from a database
Database Interrogation types (1. Query language, 2. Report generator )
• Query language: (1. SQL, 2. Graphical Queries , 3. Natural Queries)
• SQL (Structured Query Language) an international standard query language.
– SQL language is a combination of DDL, DML and the SELECT statement
• Graphical Queries : Point-and-click methods
• Natural Queries : similar to conversational English
– Graphical and Natural Queries are translated by the software into SQL
commands.
• Report generator : presents information you request as a report
Database Maintainence: to add, delete, update, and correct the data in a database.
Database Development concepts
• Database Development: to definie and organize the content, relationships, and
structure of the data needed to build a database.
• Metadata: data definitions and specifications of the data contents, relationships and
structure
• The metada are stored in data dictionary and maintained by DBA
• Data dictionary: Data base catalog containing metadata
• Data Definition Language (DDL): Modify the database objects relationships, structure
and specifications
• Database Administrator (DBA): who is In charge of database development and
maintaining the metadata using the DDL
Database application development concepts
• Database application development: to develop prototypes of queries, data entry
screens, forms, reports, and Web pages for a proposed custom application that
accesses a database to find and update the data it needs.
• Data Manipulation Language (DML): modify stored data but not the database
objects.