Introduction to Database Flashcards
What is Database?
-Is a collection of data or information which is stored in a logical and structured way.
-“A shared collection of logically related data (along with a description of this data), designed to meet the information needs of an organisation”
-A single repository of data that can be used simultaneously by many departments and users
-As well as holding the organisation’s operational data, the database holds a description of this data. For this reason, a database is also defined as a self-describing collection of integrated records. The description of the data, that is the meta data is known as the system catalogue or data dictionary
What is Database used for?
-To store
-To organise
-To manipulate data (adding, deleting, updating)
Examples of non-computerised database:
-Dictionaries
-Telephone directories
-Address books
Examples of computerised database
-Netflix
-Cellphone contacts
-Game library
-Amazon
-Facebook
Common database applications
-Banking
-Airlines
-Universities
-Sales
-Manufacturing
-Human resources
Some popular database software
-Oracle
-Microsoft SQL
-MySQL
-Microsoft Access
Database software is sometimes called:
-Database manager
-Database management system (DBMS)
Some of Data Models in DBMS
-Relational Model
-Hierarchical Model
-Object-Oriented Data Model
Relational Database Model
-A data model attempts to represent the data requirements of the organisation (or some part)
-It should provide an integrated collection of concepts for: describing data, relationships between data and constraints on the data used by an organisation.
-Each line or row in a table is called a Record
-Each should have a unique field that is called Primary Key
-The Primary Key of one entity is the Foreign Key in another entity.
Structural Components of Relational Models
-Field (Attribute)
-Record (Tuple)
-File (Relation)
-Domain
-Relational database
Field
-Each of these (name, address, etc.) is one piece of information about you
-Each of these different types of information is called a “Field”
Record
-All of the fields are put together to make a “record”
-A record is therefore all of the data about one person in a table
File
-All of the records are stored together in a “file”
-A file consists of a collection of particular records
Domains
-Every attribute in a relational database is associated with a domain
-It allows us to define the meaning and source of values that attributes can hold.
A field or a collection of fields is designated as the __________ to provide uniqueness
Primary key
A ______________ is a collection of tables that are related to one another based on a common field
Relational Database
When the primary key of one table is represented in a second table to form a relationship, it is called
Foreign key
What is Database Management System (DBMS)?
-Consists of programs that control the database structure and access to the data
-Information changes only have to be updated once
-A change only needs to be entered once and the information is updated in any relevant file
Functions of DBMS
-Data storage, retrieval and update
-Concurrency control services
-Recovery services
-Security
Data about data is normally termed as:
Metadata
Table is synonymous with the term:
Relation
Which of the following is true?
a. A relational table cannot have more than one column made of primary key
b. A relational table can have two columns made of primary key
c. A relational table may not have a primary key
d. b and c
c. A relational table may not have a primary key
A property of the relational table is that:
Each column has a distinct name
In a relational model, relationships between tables are created by using
Primary keys
