CIT452 Chapter 1-3
structural dependence
Access to a file is dependent on its own structure, All file system programs are modified to conform to a new file structure
•Explain why the data dictionary is sometimes called "the database designer's database."
Just as the database stores data that is of interest to the users regarding the objects in their environment that are important to them, the data dictionary stores data that is of interest to the database designer about the important decisions that were made in regard to the database structure. The data dictionary contains the number of tables that were created, the names of all of those tables, the attributes in each table, the relationships between the tables, the data type of each attribute, the enforced domains of the attributes, etc.
Row
Tuple
physical independence
When you can change the physical model without affecting the internal model
logical independence
When you change the internal model without affecting the conceptual model
database management system (DBMS)
a collection of programs that manages the database structure and controls access to the data stored in the database
Business intelligence
a comprehensive approach to capture and process business data to generate information that support decision making
Data management
a discipline that focuses on the proper generation, storage, and retrieval of data
superkey
a key that can uniquely identify any row in the table
secondary key
a key that is used strictly for data retrieval purposes and does not require a functional dependency
Big Data
a movement to find new and better ways to manage large amounts of web- and sensor-generated data and derive business insight from it
JOIN
allows information to be intelligently combined from two or more tables
PROJECT
an operator used to select a subset of columns
SELECT
an operator used to select a subset of rows
DIFFERENCE
an operator used to yield all rows from one table that are not found in another union-compatible table
INTERSECT
an operator used to yield only the rows that are common to two union-compatible tables
index
an orderly arrangement to logically access rows in a table
schema
conceptual organization of the entire database as viewed by the database administrator
network model
created to represent complex data relationships more effectively than the hierarchical model, to improve database performance, and to impose a database standard
internal schema
depicts a specific representation of an internal model, using the database constructs supported by the chosen database
operational database
designed to support a company's day-to-day operations
data definition language (DDL)
enables the database administrator to define the schema components
Data independence
exists when data storage characteristics are changed without affecting the program's ability to access the data
Structural independence
exists when you change the file structure without affecting the application's ability to access the data
Full functional dependence
functional dependencies in which the entire collection of attributes in the determinant is necessary for the relationship. Required for 2NF.
composite key
key that is composed of more than one attribute
natural join
links tables by selecting only the rows with common values in their common attribute(s)
Equijoin
links tables on the basis of an equality condition that compares specified columns of each table
Theta join
links tables using an inequality comparison operator
Inner join
only returns matched records from the tables that are being joined
physical model
operates at the lowest level of abstraction, describing the way data is saved on storage media
DIVIDE
operator is used to answer questions about one set of data being associated with all values of data in another set of data
conceptual model
represents a global view of the entire database by the entire organization
desktop database
single-user database on a personal computer
workgroup database
supports a small number of users or a specific department
enterprise database
supports many users across many departments
XML database
supports the storage and management of unstructured XML data
Database design
the activities that focus on the design of the database structure that will be used to store and manage end-user data
Entity integrity
the condition in which each row in the table has its own known, unique identity
Structured Query Language (SQL)
the de facto query language and data access standard supported by the majority of DBMS vendors
external model
the end users' view of the data environment
unique index
the index key can have only one pointer value associated with it
index key
the index's reference point that leads to data location identified by the key
subschema
the portion of the database "seen" by the application programs that produce the desired information from the data within the database
the 3 Vs
volume, velocity, and variety
composite entity
•The many-to-many (M:N) relationship can be implemented by creating a new entity in 1:M relationships with the original entities
Referential integrity
•a condition by which a dependent table's foreign key entry must have either a null entry or a matching entry in the primary key of the related table
Extensible Markup Language (XML)
•a language used to represent data elements in textual format
candidate key
•a minimal superkey; that is, a key that does not contain a subset of attributes that is itself a superkey
data model
•a relatively simple representation of more complex real-world data structures
database
•a shared, integrated computer structure that stores a collection of the following: −End-user data - that is, raw facts of interest to the end user - Metadata, or data about data, through which the end-user data is integrated and managed
relvar
•a variable that holds a relation −It is a container (variable) for holding a relation data, not the relation itself −The term is short for relation variable
UNION
•an operator used to merge two tables into a new table, dropping duplicate rows •The tables must be union-compatible
PRODUCT
•an operator used to yield all possible pairs of rows from two tables Also known as the Cartesian product
Data
•consists of raw facts −The facts have not yet processed to reveal meaning to the end user
hierarchical model
•developed in the 1960s to manage large amounts of data for complex manufacturing projects −The hierarchical structure contains levels, or segments
data anomaly
•develops when not all of the required changes in the redundant data are made successfully
Data dependence
•exists when all data access programs are subject to change when data storage characteristics change
NoSQL
•new generation of DBMS that is not based on the traditional relational database model −These databases are designed to handle an unprecedented volume of data, variety of data types and structures, and velocity of data operations of new business requirements
database system
•organization of components that define and regulate the collection, storage, management, and use of data within a database environment
Data modeling
•the process of creating a specific data model for a determined problem domain −Data modeling is an iterative, progressive process
internal model
•the representation of the database as "seen" by the DBMS −The internal model requires a designer to match the conceptual model's characteristics and constraints to those of the selected implementation model
Information
•the result of processing raw data to reveal the meaning of data −To reveal meaning, information requires context
Functional dependence
•the value of one or more attributes determines the value of one or more other attributes
•The database system is composed of the following five components:
−Hardware −Software −People −Procedures −Data
data manipulation language (DML)
−defines the environment in which data can be managed and is used to work with the data in the database
Outer join
−matched pairs are retained and unmatched values in the other table are left null §Left outer join: yields all of the rows in the first table, including those that do not have a matching value in the second table §Right outer join: yields all of the rows in the second table, including those that do not have matching values in the first table
analytical database
−stores historical data and business metrics used exclusively for tactical or strategic decision making and is comprised of two main components: §The data warehouse stores data in a format optimized for decision support §Online analytical processing (OLAP) is a set of tools for retrieving, processing, and modeling data from the data warehouse