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
Primary key is equivalent to:
a. Master key
b. Private key
c. Key
d. Foreign key
c. Key
A table with columns and rows is sometimes called
A relation
Which of the following relates to referential integrity?
a. No column of a primary key can be null
b. A column can be currently unknown
c. Rules that define or constrain some aspect of the data used by the organization.
d. None of the above
a. No column of a primary key can be null
_______states that primary keys should not be null
Entity Integrity
A _____ is a shared collection of logically related data, designed to meet the information needs of an organisation.
Database
DBMS stands for:
Database Management System
Which of the following is an advantage of the DBMS?
a. Improves data integrity
b. Sharing of data
c. Improved data independence
d. All of the above
d. All of the above
