Module 1: Introduction to Databases and Transactions Flashcards
Is shared collection of logically related data (and a description of this data), designed to
meet the information needs of an organization
Database
Database is composed of:
Entities and Relations
Is a collection of application programs that perform services for the end users
such as the production of reports
File-based System
5 Limitations of the File-based Approach
- Separation and Isolation of Data
- Duplication of Data
- Data Dependence
- Incompatible File Formats
- Fixed Queries/Proliferation of Application Programs
The Limitations of the File-based Approach can be attributed to two factors:
- Definition of data embedded in the application programs, rather than being stored separately
and independently - There is no control over the access and manipulation of data beyond that imposed by the
application programs
- Is software designed to assist in maintaining and
utilizing large collections of data - A general-purpose software system that facilitates the processes of defining,
constructing, & manipulating databases for various applications
Database Management System or DBMS
A database involves specifying the data types, structures, and constraints for the
data to be stored in the database
Defining
The database is the process of storing data itself on some storage medium that
is controlled by the DBMS
Constructing
A database includes such functions as querying the database to retrieve specific
data, updating the database to reflect changes in the miniworld, & generating reports from
the data
Manipulating
Is a software that enables user to define, create and maintain that database and which
provides controlled access to the database
DBMS
DBMS provides the following facilities:
- Allows users to define the database through DDL (Data Definition Language)
- Allows user to insert, update, delete and retrieve data through DML (Data Manipulation
Language) - Provides controlled access to the database.
Provides controlled access to the database
DBMS
DBMS may provide:
- A security system, which prevents unauthorized users from accessing the database
- An integrity system, which maintains the consistency of stored data
- A concurrency control system, which allows shared access of the database
- A recovery control system, which restores the database to a previous consistent state following a hardware or software failure
What are we going to cover?
- How do we represent the world with a database?
Database Design and Application Development
What are we going to cover?
- How can we answer questions about enterprising this data?
Data Analysis
What are we going to cover?
- How does a DBMS allow many users to access data concurrently, and
how does it protect against failures?
Concurrency and Robustness
What are we going to cover?
- How does the database cope with large amounts of data?
Efficiency and Scalability
Who created the first general purpose DBMS Integrated Data Store, where and when?
Charles Bachman; at GE; early 1960s
It creates the basis for the network model (standardized by CODASYL)
DBMS Integrated Data Store
Develops the Information Management System (IMS)
IBM
_____ uses and alternate model, called the _____.
Information Management System (IMS); Hierarchical Data Model
Is created around IMS
SABRE
Who from IBM creates the relational data model and when?
Edgar Codd; 1970
In _____, Codd receives the _____
for his contributions to database theory.
1981; Turing Award
In _____, _____ developed by IBM, becomes the standard query language for databases
1980s; SQL
SQL is
standardized by
ISO
In _____ and _____, IBM, Oracle, Informix and others develop powerful _____.
1980s and 1990s; DBMS
In the _____, DBMS are showing how useful they can be.
Internet Age
4 Forms of Data
- Text
- Image
- Audio
- Video
4 Data Sources
- PC
- Web
- Phone
- Bar Code
- Are data that describe the properties of data (but do not include that data)
- Allow database designers & users to understand what data exist, what the data mean
and what the fine distinctions are between seemingly similar data items
Metadata
12 Advantages of Why we use DBMS
- Control of data redundancy
- Data consistency
- Sharing of data
- Data integrity and security
- Enforcement of Standards
- Economy of scale
- Balanced conflicting requirements
- Data independence
- Efficient data access
- Data administration
- Concurrent access and crash recovery
- Reduced application development time
7 Disadvantages of Why we use DBMS
- Complexity
- Size
- Cost of DBMS
- Additional hardware costs
- Cost of conversion
- Performance
- Higher impact of a failure
- Is responsible for the management of the data resource including database planning, development
and maintenance of the standards, policies and procedures and logical database design - Consults with and advises senior managers, ensuring that the direction of database development will
ultimately support corporate objectives
Data Administrators
Is responsible for the physical realization of the database system, including physical database design
and implementation, security and integrity control, maintenance of the operational system and
ensuring satisfactory performance for the applications and users.
Database Administrators
Two Types of Designers
- Logical Database Designer
2. Physical Database Designer
- Is concerned with identifying the data, the relationships between data and the constraints on
the data that is to be stored in the database. - Must have a thorough and complete understanding of the organization’s data andof the
business rules.
Logical Database Designer
Takes the logical data model and decides how it is to be physically realized
Physical Database Designer
Physical database designer involves:
- Mapping the logical data model into a set of tables and integrity constraints;
- Selecting specific storage structures and access methods for the data to achieve
good performance for the database activities; - Designing any security measure required on the data.
- Responsible in the implementation of the application programs that provide the required
functionality for the end users. - Work from the specification produced by systems analyst.
Application Programmers
- Are the clients for the database – the database has been designed and implemented, and is being maintained to server their information needs.
End Users
End users can be classified according to the way they use the system:
- Naive Users
2. Sophisticated Users
- Are typically unaware of the DBMS.
- They invoke database operations by entering simple commands or choosing options
form a menu.
Naive Users
- Familiar with the structure of the database and the facilities offered by the DBMS.
- May use a high-level query language such as SQL to perform the required operations.
Sophisticated Users
Is a collection of high level description constructs that hide many low-level
storage details
Data Model
Most current DBMS use the _____.
Relational Data Model
The central data description in this model is the _____ (_____ - same as in set theory mathematics).
Relation; A Set of Tuples
For convenience, we refer to each tuple as a _____.
Row
Is a description of the data in terms of the data model
Schema
In the relational model the
schema looks like:
RelationName(field1 : type1, …, fieldn : typen)
- Is the abstract graphical representation of an enterprise
- Usually the beginning of database development
Enterprise Data Model
Is language-independent. It can be drawn using a pen and a paper.
Data Modeling
Purpose of Enterprise Data Model
It creates an overall picture or explanation of organizational data NOT the design of the database
4 Data Modeling Tools
- Entity Relationship Diagram
- Unified Modeling Language
- Data Flow Diagram
- Data Dictionary