2. The Database Environment Flashcards
What are the components of the database environment?
- Users
- Database management system (DBMS)
- Physical database (including hardware and data)
What does the database management system diagram look like?
From multiple users -> multiple application softwares -> single database management software -> single physical database
What is the mnemonic for advantages of a database?
Red cost Intel secure independence, Stanley accessed.
What are the advantages of a database ?
- Reduced data redundancy
- Lower capturing costs, data entered once
- Integrity of data maintained, updates occur same place
- Increased security, centrally controlled
- Data is independent from application software
- Standardization of data structures
- Access to data is easy
What is the mnemonic for disadvantages of a database?
Costa complexly times failures
What are the disadvantages of databases?
- Costs to start up
- Complex to design and use
- Time-consuming to design
- Failure of the database would mean failure of application software and may result in shut down of organization
Who are the various database users?
- End user
- Application programmer
- Database administrator
- Data administrator
How do end users use the database?
They capture data and extract informatiom
Low skill level, they use application software
What are application programmers responsible for?
Creating, maintaining, updating and managing application and DBMS software
What is the responsibility of the database administrator?
Managing and controlling the database
What is another name for a data administrator?
Database analyst
What are data administrators responsible for?
Controlling and managing data
Manage integrity of data by setting standards
What is DBMS?
Integrated set of software that provides a user friendly interface to users
What is an example of DBMS?
Microsoft access
What are the levels of the three-level database architecture?
- External level
- Conceptual level
- Internal level
What is another name for the external level of architecture?
User view
What is the external level?
End users view of data and database
How many view can the external view have?
An infinite amount
E.g. Cash clerk will have a different input screen than a credit sales clerk etc.
What is the conceptual level?
A complete view of the entire database and all the data
Who normally uses the conceptual view?
The database administrator
How many variations are there of the conceptual view?
Only one
What is another name for the internal level?
Physical view
What is the internal view?
It is the low level view of how the data is stored physically. E.g. Harddrive etc.
How many physical views are there?
Only one
How is binary code concerned with the physical view?
Binary code is only one facet of the physical view
Who updates and manages all levels of database architecture?
The database administrator
What are the key components of the DBMS?
- Data dictionary
2. Data language
What is a data field?
A single data value, it is the smallest unit of data
What is a data dictionary?
Contains records for each data field and provides detailed description of each data field
What are database languages used for?
The users to interact with the database
What are the database languages included?
- Data definition language
- Data control language
- Data manipulation language
- Data query language
What is SQL?
Structured query language and combines all previously mentioned languages
What is the data definition language used for?
Define a database and includes commands to:
- Create, modify and delete database and it’s objects
- Define and describe data structure
- Create data dictionary
What are data objects?
- Tables
- Views
- Rules
- Indexes
Who usually uses DDL?
The administrator
What is the purpose of the data control language?
Used to control security and access to database objects and data