CIS 112 Exam 1 Flashcards
- Gets collected
- Quantitative or Qualitative
- Can (is for this course) be structured in tidy tables
- Ex.- grey, truck, right
Black, suv, left
Data
- Generated
- Ex.- Beau street is open
Information
________ is stored in a database
Data
4 Criteria to store data
- Representative of Data
- Logical/ Internally Consistent
- Has a defined purpose
- Queryable (Has to be accessible)
________ are logically/internally consistent!
Databases
A tool that imposes the 4 criteria on any data we store
Database Management System
The idea of only storing the minimal amount of data to be truly representative of the data set without being repetitive
Data Dependency/ Data Redundancy
Splitting large data sets into smaller, connected tables.
Data Dependency/ Data Redundancy
- Open source
- Stored in one place but multiple interfaces can pull from it
Data Independence
Accordingly, it provides a basis for a high level data language which will yield maximal independence between programs on the one hand and machine representation and organization of data on the other.
Data Independence
- Every column always gets a unique name.
- Columns represent attributes.
- Rows represent entities.
- Every row must be unique and identifiable (index = primary key)
- Cells contain atomic data or null pointers.
- Attributes must be stored in the same format.
- The ordering of rows and columns is unimportant.
Codd’s Relational Model Criteria
break it into the smallest bit
atomic
The process of removing redundancies by organizing into a well-organized schema of relations connected by keys which constrain/document the functional dependencies of the data.
Normalization
a relationship between two sets of attributes in a database, where one set (the determinant) determines the values of the other set (the dependent)
Dependency
If (A,B) → (C,D,E), and (A) → (D), then (A) → (D) is the _______.
partial dependency
If (A) → (B) and (B) → ( C ), then (B) → ( C ) is the ________.
transitive key
Something we declare so we can insure our database is normalized
keys
The set of columns we need to look at to determine which is which
Primary key
Two columns we look at
Composite key
An attribute/primary key that appears in multiple tables to tell us more information
Foreign Key
A type of structural diagram for use in database design
Entity Relationship Diagram
Contains different symbols and connectors that visualize two important information:
- The major entities within the system scope.
- Inter-relationships among these entities.
Entity Relationship Diagram
Weak relationships are connected by ________
dotted lines
A series of connected components which produce information through specific procedures abiding by specific rules.
Information system
Is a storage component of an information system.
Database
plan to solve
scope
what prevents you/constraints
boundaries
In the middle of System Development Life Cycle (Is a circle with arrows) is _______.
Ethics and Users
System Development Life Cycle
- System Definition
- Requirements Analysis
- Component Design
- Implementation
- Maintenance
User needs assessment
- Ex.- Who will be using the system and their accessibility to the system
- What kind of roles will need to be created, trained, hired, etc.,
- Hardware specifications
Requirements Analysis
- Design/plan for all components AND the way they will work together
- Prototyping (Ex.- Excel file)
Component Design
Build, Test, Document
Implementation
Monitoring the continued usability of the system
- Ex.- Is it meeting my clients needs?
Maintenance
specifies ’how many’ rows will connect between the tables
Cardinality
Any attribute or set of attributes which uniquely identify each entity.
Candidate Key
The developer-chosen candidate key
Primary Key
Any non-primary candidate key; typically used as an index.
Secondary Key
A primary key from an external relation.
Foreign Key
Any key comprised of more than one attribute.
Composite Key
Documents the entities and the cardinality of their relationships.
Conceptual
Documents the attributes which establish the formal connection between entities.
Logical
Documents the way the schema is stored, including attribute data types and constraints.
Physical
ERD’S will also be __________; key constraints will appear first, then attribute names, then the data type, followed by any non-key constraints. The table name will always appear above the attributes. We will not enforce any particular rounded corners– boxes are an excellent representation for our purposes.
standardized
an option of two
binary
the smallest possible unit which can be interpreted
bit
the smallest common unit which can be addressed
for processing or storage
byte
A single character (e.g., letter, number, or symbol). Requires 1 byte.
CHAR
A collection of characters to form a string. Variable size; one byte per character, with a maximum
size typically enforced by the database management system.
TEXT
A whole number,either positive or negative, which has no digits after a decimal point. Usually
4 bytes, but can be smaller or larger as needed.
INTEGER
- A numeric value with ’floating point precision’, meaning that it adjusts the location of the
decimal point as needed to support the provided precision (P, or the number of significant digits needing to be stored). - Minimum of 4 bytes, but can be larger as needed to support the required precision.
Database Management Systems treat floating-point data as inexact, meaning that sometimes they’ll approximate the value rather than store it explicitly. This can cause errors for some calculations! Other data types, such as MONEY, exist to be exact for cases where slight differences can make substantial impact in analysis
FLOAT(P)
A binary choice; True or False, Yes or No, On or Off. Requires 1 byte.
BOOLEAN
The attribute is limited in some way (ex: can never be negative)
CHECK
The attribute is not permitted to contain a NULL value.
NOT NULL
The stored value of the attribute may not match any other entity’s value for this attribute.
UNIQUE
The chosen candidate key of the table; enforces NOT NULL and UNIQUE constraints.
PRIMARY KEY
A primary key from an existing table; enforces a NOT NULL constraint.
FOREIGN KEY
Optional connection; at most 1 connecting row:
——O—l—
Zero to one
Mandatory connection; only 1 connecting row:
—–l–l—
Exactly one
Optional connection; could be more than one row:
——-o<- ——-
Zero to many
Mandatory connection; at least one row, but could be more:
———l<- ——-
One to many
It is vitally important to remember that both ends of every relationship have a _______!
foot
A _________ will relate data common to a single entity.
row (a.k.a. record, tuple, or n-tuple)
A ________ will relate data common to a single attribute.
column (a.k.a. field or domain)
A _____describes the attribute for a given entity
cell
A __________ will preserve the connections between entities and their attributes
table (a.k.a. file or relation)
___________ are connections between stored data. In such a case, for every entity there is an attribute or a set of attributes which are dependent on a determining attribute or set of attributes.
Functional dependences
A minimal set of attributes which can uniquely identify entities in the table.
Candidate Key
An attribute or set of attributes chosen in the DBMS to uniquely identify entities within the table.
Primary Key
An attribute or set of attributes which represent the primary key of any table outside of the current table.
Foreign Key
A set of more than one attribute which act as a key when together, but not when examined alone.
Composite Key
An attribute or set of attributes which can uniquely identify entities in the table but is instead used in the DBMS to further sort stored data for faster queries.
Secondary Key
What relationship exists between a candidate key and a functional dependency?
Every non-key attribute in a table is functionally dependent on a candidate key.
A ________ functional dependency occurs when a functional dependency exists between a subset of the determining attributes and a subset of the dependent attributes.
partial
A ________ functional dependency occurs when the dependent attribute of a functional dependency is the determining attribute of another.
transitive
is the process of choosing to allow some redundant data in service of the end-user
denormalization
Dataset organization follows all criteria of Codd’s Relational Model.
First Normal Form (1NF)
All transitive functional dependencies have been removed; the determinant of every attribute is the complete primary key of its containing table.
Third Normal Form (3NF)
All partial functional dependencies have been removed; any attribute dependent on the primary key needs all pieces of the primary key to be determined.
Second Normal Form (2NF)
A ________ is a collection of relational tables with referential integrity, meaning that the connections between tables are defined by the foreign keys.
schema
Normalization generally requires taking a single table and creating a schema based on the results. Each time I create a new table in the schema, I will create a _______ key in the new table and leave a copy of it behind as a _________ key.
primary; foreign
The following string of bits stores a positive INTEGER: 10100111. What is the integer?
167
Organizing the mechanisms for information flow throughout the system and determining the hardware and software needs of the system.
Component Design
Building the system; purchasing hardware and software, converting prior systems to the new design, building and testing the components of the system, producing reference materials and documentation, and testing the completed system prior to rollout.
Implementation
Updating documentation with changes, evaluating the client’s use of the system, performing upgrades to the system infrastructure, and confirming client satisfaction.
Maintenance
Communicating with the client abound the choice of information system, evaluating existing systems, collecting representative samples, or otherwise investigating the client’s needs.
Requirement Analysis
Choosing an information system which best suits the scope and boundaries of your client.
Definition
A ______ is a component in an information system which is responsible for rigidly structuring input data and efficiently producing validated results when queried.
database
The concept of ______ allows us to construct ERDs that function as blueprints – they have a clear beginning that matches our intuition, and we can follow the “map” of the ERD to ensure that table construction and data manipulation occurs in the proper order to work within our well-constrained database.
flow
A _____________ relationship is one in which there is an existence-dependent connection to another table; we usually draw this with a dotted line. All other relationships are considered _______ because they do not depend on the existence of a connected row.
weak; strong
