AIS Week 4
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. What would you like to do?
What is a database?
A set of interrelated, centrally coordinated files.
What does DBMS stand for?
Database Management System
What is a database management system (DBMS)?
Na interface between a database and various application programs.
What does a database administrator (DBA) do?
Look after and be responsible for the database.
What is a data warehouse?
A set of detailed and summarised data that is used for analysis rather than transaction processing.
What is involved in business intelligence?
Using data warehouses for strategic decision making.
What does OLAP stand for?
Online Analytical Processing
What is online analytical processing (OLAP)?
Using queries to guide an investigation of hypothesised relationships in data.
What is data mining?
Using statistical analysis to 'discover' unhypothesised relationships in data.
What are the 5 advantages of a database system?
- Data integration
- Data sharing
- Minimal data redundancy & inconsistencies
- Data independence
- Cross-functional analysis
How many separate views are there of a database system and what are they called?
2. A logical view and a physical view.
What is the logical view of data in a database system?
How people organise and understand data.
What is the physical view of data in a database system?
How and where the data is physically stored.
How many levels of schemas are there and what are they called?
3. Internal, conceptual and external.
What is the external level schema?
Individual logical views of portions of the database.
What is the conceptual level schema?
Enterprise wide view of the entire database.
What is the internal level schema?
Details about data storage. Eg definitions, indexes etc.
What is a data dictionary?
Information about the structure of a database.
What does a schema describe?
The logical structure of a database.
What does DDL stand for?
Data Definition Language
What is data definition language (DDL)?
Builds a data dictionary, creates a database, describes a logical view for each user.
What does DML stand for?
Data Manipulation Language
What is data manipulation language (DML)?
Changes the database content - updates, insertions and deletions.
What does DQL stand for?
Data Query Language
What is data query language (DQL)?
Enables users to retrieve, sort, order and display data.
What is another work for a row of data in a relational database?
What is a relational data model?
A representation on database contents. Shows the conceptual and external level schemas as if data is stored in tables.
What is a primary key?
A database attribute that uniquely identifies a specific row in a table.
What is a foreign key?
An attribute that is a primary key in another table that is used to link tables.
What are the 4 basic requirements of a relational database?
- There can only be one value per cell
- Primary keys cannot be blank
- Foreign keys must correspond to primary keys in other tables
- All other attributes must be characteristics of what is described by the primary key
What does 3NF stand for?
Third Nominal Form
What does third nominal form (3NF) mean?
The table is free of update, insert and delete anomilies.
What is an update anomaly?
When data is keyed more than once and not updated in all places.
What is an insert anomaly?
When there is no way to store data that has blank fields.
What is a delete anomaly?
When deleting data deletes all data about that entity.
What is the referential integrity rule?
When foreign keys link tables to ensure database consistency.
What would you like to do?
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