Exam #2: Database Management Systems

What is the order of the data hierarchy from lowest to highest

Bit → Byte → Field → Record → File → Database

What is a database?

Centralize and control data

What does a database management system do?

• Interfaces with?

• Separates?

• Solves problems of?

Applications and Physical Data Files

Separates logical and physical views of data

Traditional file environment

• Control redundancy

• Eliminate incosistency

• Uncouples programs and data

• Enables organization to centrally manage data and data security

What are relational data base management systems?

They represent as two-dimensional tables called relations or files

Each table contains data on entity and attributes

What are the parts of a table in DBMS?

Rows (Tuples) - Records for different entries

Fields (Columns) - Represent attribute for entity

Primary (Key) - Field in table used to uniquely identify a table

Foreign Key: Primary key used in second table as look-up field to identify records from original table

Data Definition Language (DDL)

Structures database content, create tables, define characteristics of fields

Data Dictionary

Automated or manual file storing definitions of data elements and their characteristics

Data Manipulation Language (DML)

Used to add, change, delete, and retrieve data from the database

• SQL

What is an entity-relationship diagram?

Used by database designers to document the data model

Illustrates relationships between entities

What are the types of cardinality of relationships?

One-to-One: Each instance will have one related instance

• Employee and parking space

One-to-Many: Instance on one side can have many related instances, but an instance on the other side will have a max of one related instance

• Product line and product

Many-to-Many: Both sides can have many related instances on the other sides

• Students and courses

What do very large databases and systems require?

Special capabilities/Tools

• Analyze large quantities of data

• Access data from multiple systems

How do databases get information?

Data warehousing

Data mining

What is a data warehouse?

Stores current/historical data

Consolidate/Standardize information

• cannot be altered

Provide query, analysis, and reporting

What is a data mart?

Type of data warehouse:

• Focus on portion of firm’s date for use for specific population

• Focus on single subject

What is text mining?

Extracting key elements from large unstructured data sets

• Like e-mails

What is a data quality audit?

Survey of accuracy and level of completeness of data:

• Survey samples from data files

• Survey end users for perceptions of quality

What is data cleansing?

Software to detect and correct data that are incorrect, incomplete, improperly formatted, or redundant