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Data Storage and Extraction (Information Quality (Consistency ((connected…
Data Storage and Extraction
Information Quality
Timeliness
the difference between the current time and when the data was stored
Accuracy
Is this information correct?
Completeness
Is all or part of a value missing?
Uniqueness
Happens when the exact same piece is sorted multiple times
Consistency
(connected to uniqueness, but not the same)
Bugs are common
Types of Information
Analytical Information
refers to any data or information that can be used to make intelligent inferences relevant to the organization, help solve unstructured business problems, and support higher-level, ad-hoc decision making.
Transactional Information:
refers to the data that is generated by real-time business processes
Operational Database:
Stored/ required for everyday business processes or operations.
Levels of Granularities
Coarse/ Aggregate
Data has been summarized even further.
FINE
Information is in raw data form
Databases:
are collections of data organized for search and retrieval
DBMS (Database Management Systems)
: the software system used to store data electronically and provide advanced features for ensuring and maintaining data quality as well as managing the security and availability of the data
Example: Access, SQL Server, Oracle, DB2, or others.
Relational Databases: Resolves the problem of data redundancy
DATA MODELING AND TABLE MAPPING
Conceptual data
model is constructed through collaboration with the business stakeholders to reflect the initial business requirements that the data must support.
Entity-Relationship Diagramming (ERD)
It includes specific standardized notation to indicate each piece of data that needs to be included in the system as well as how the data should be organized and separated to maintain the highest quality (e.g. maximizing the speed of data access and reducing data redundancy).
Entities:
are persons, places, or things about which an organization wishes to save information. (A Concept)
a logical concept in the mind of the analyst that represents a category of objects that have common characteristics or attributes that we want to store. For example, when we think about police detectives we have a concept--a logical abstraction--in our mind that represents a type of person who investigates crimes.
Example: Employee, Order, and Time Sheet
Rectangular boxes
When we label entities, we use the singular tense because each entity represents a category.
Attributes:
(Properties) These are the properties that the entities care about. They are characteristics of the entities
Color, Employment Date, Name, and Social Security Number.
Relationships:
verbs that describe how entities relate to each other; for example (the relationships are capitalized), 'Customer BUYS Product,' 'Employee FILES Time Sheet,' 'Salesperson PLACES Order.' An entity-relationship-entity phrase is called a "relationship entity pair," which is a fashionable mechanism for representing relationships. Relationship entity pairs are bidirectional. Therefore, 'Customer Buys Product' is the same as 'Product is Bought by Customer.'
Diamonds represent
Cardinality
usually expressed as simply "one" or "many."
For example, a husband can have only one wife, while a parent can have many children
1:1
1:M
M:M
Maximum VS. Minimum
Instances:
(A Single Occurrence) :
Data modeling
is the process used to define data requirements needed to support the business processes within organizations.
physical data model
