data views (Know 2 views – ways of viewing)
“1. physical view
Focuses on the actual format and location of the data. Typically only very spexialized computer professionals are concerned with the physical view.
Focuses on the meaning, content and context of the data.
Group of related characters. “corcoran” would be a data field for the Last name of a student. Consists of the individual letters that make up the last name. A data field represents an attribute of an entity. (the columns)
A collect of related fields (rows), a collection of attirbute related to an entity.
Integrated collection of logically related tables.
primary key / key
One distinctive field, which uniquely identifies the record. For most employee databases, the key field is the employee identification umber
Data is collected over several hours, days, or weeks, and then is processed all at once as a “batch” — like credit card bills.
real-time processing / online processing
Data is processed at the same time the transaction occurs. Like requesting funds at an ATM
When organizations have multiple files on the same subject or person.
Database characteristics relating to the consistency and accuracy of data. Like if a bill for a person gets sent to their old address instead of their new one. When there are multiple sources of data, each source might have their own variations
data definition subsystem
defines the logical structure of the database by using data dictionary or schema
A specific tool in a database anagement that shows a blank record and lets you specify the information needed, like the field and values of the topic you are looking to obtain.
SQL / Structured Query Language
A program control language used to create sophisticated database applications for requesting information from a database.
DBMS (Database Management Systems) structures (Know 5 models)
One-to-many — Fields or records are structured in nodes, which are points connected like the branches or an upside-down tree. Every entry has a parent node. You start at the top and trace done. If one parent node is deleted, the child files are, too.
Many-to-many —Also has a hierarchical arrangement however each child node may have more than one parent node.
There are no access paths down a hierarchy. Rather, the data elements are stored in different tables, each of which contains rows and columns. A table and its data are called a relation.
Extend the two-dimensional data model to include additional or multiple dimensions, sometimes called a data cube. Complex relationships can be represented.
More flexible and store data as well as instructions to manipulate the data. The structure is designed to provide input for object-oriented software.
Types of databases (Know 4 types)
Collection of integrated files primarily used by just one person. Data is under the direct control of the user.
Can be stored on a central database server and managed by a database administrator. Users have access to the database through their personal computer linked to local or wide area networks.
Data in a company is stored not in just one location but in several locations and is made accessible through a variety of communications networks.
Enormous database that an organization develops to cover particular subjects. It offers this database to the public or selected outside individuals for a fee.
Csi – example of commercial database
Offers consumer and business services, including electronic mail
“Dialog Information Services –
example of commercial database”
Offers business information as well as technical and scientific information
“Dow Jones Interactive Publishing –
example of commercial database”
Provides world news and information on business, investments and stocks
LexisNexis – example of commercial database
Offers news and information on legal, public records and business issues.
Data collected from a variety of internal and external databases and stored in a database called a data warehouse. Data mining is then used to search these databases.
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