Section 6: Data Flashcards
Why do we need Database Management Systems? (DBMS)
It allows the organization to access and store all of its data for each employee so it can be easily accessed
Why do we need database research?
It allows for organizations to analyze data and make better business decisions
How are databases and the World Wide Web interconnected?
Websites interface between clients and databases, responding to client requests.
(Client sends a request to the server, the web servers search a database, organize the results in a web page, finally it sends that page to the client)
How many layers are in the DBMS?
What are they and explain what they do.
1) Application Layer - Communicates w/ the end user and can be fairly complex (Receives request, sends request to DBM Layer)
2) Database Management Layer - Holds data in data tables (records and fields) as well as fulfills requests sent by application layer.
What are records and fields in a data table?
Records = Rows
Fields = Columns
Name the different types of Data.
Integers - Whole Numbers (1,2,3,4)
Floating Point Numbers - Numbers stored as decimals (1.34, 2.67)
Characters - Letters and other types of characters (D, #, l , k , !)
Character Strings - String or combination of Characters (dsfoihei!@#$Ssfd#)
Boolean Values - Yes or No values (True / False)
What is a flat-file database?
How does it store data?
A simple data table. A flat-file database can not contain multiple tables
Stores data as a plain text file
What is a hierarchical database?
Stores data in a tree like structure. There is one parent for each record.
What is a segment in a hierarchical databse?
It is an optional node that forms a sub-tree
What is a relational database?
Tables that can be joined in logical ways.
What is a primary key?
A unique identifier that creates the relationship among tables. Typically a field not record
What is a foreign key?
When a primary key is marked on one table but is also found on another table. That second primary key is the foreign key.
What are Object-Oriented databases (OO)?
Stores complex data and relationships between data directly w/out user inter-table relations
What are NoSQL databases?
Not only SQL.
Can accommodate a wide variety of data models
- Key-value
- document
- columnar
- graph formats
What are graph stores?
Used to store information about networks of data (social connections)
What are wide-column stores?
Stores are optimized for queries on large data sets and store columns of data together, instead of in rows
What is a document-format database
Pair each key with a complex data structure known as a document (Documents can contain many different key-value pairs)
What are distributed databases?
Consists of data residing on different machines
What are SQL statements used for?
Queries that identify what data should be retrieved or how the data should be manipulated
How does SQL and the database server interconnect?
DBMS provides a mechanism to send the code to and from the database server
What does the selection operation do?
Takes rows from one table and creates a new table
What does the keyword ‘SELECT’ do?
Identifies the records that are being requested
What does the keyword ‘FROM’ do?
Identifies the table name
What does the keyword ‘WHERE’ do?
The condition the query is requesting
What does the ‘*’ do?
Everything from the table is selected
What is the ‘UNION’ operation?
Combines distinct fields from multiple tables that have the same set of attributes and data types
What is the ‘PRODUCT’ operation?
Creates a result table that includes all of the attributes from the two tables
What is the ‘JOIN’ operation?
Combines two tables, but records are only appended when a matching criterion is met
What are the DBA responsibilities?
1) Security
2) Tuning
3) Availability
4) Continuity
5) Backup and recovery
6) Reporting
7) Design and develop database applications
What is business intelligence?
Using collected data to assist in making predictions and decisions that will increase profits.
