Card Set Information
AIS Accounting Information Systems ch4
Accounting Information Systems, ch4
What is a database?
Related group of files.
What is a file?
Related group of records.
What is a record?
Related group of fields.
What is a field?
Attributes of an entity.
Describe the data hierarchy.
What are some advantages of database systems?
- Data integration
- Data sharing
- Minimizing of data redundancy/inconsistency
- Data independence
- Cross-functional analysis.
What does DBMS stand for and what is it?
Database Management System
= interface between software app and data files.
What does DBA stand for and what is it?
= person responsible for maintaining the database (most contact will be with this person).
What is a data dictionary?
Information about the structure of a database (field names, descriptions, uses etc).
What are 2 typical views of a database?
How and where data is physically arranged and stored in the computer system
How people conceptually organize and understand data.
What is a schema and what are the 3 levels of schemas?
Describes the logical structure of a database
- External level
- Conceptual level
- Internal level.
What is the external level of a schema?
Individual users view of the data/portions of the database; each view is a subschema.
What is the conceptual level of a schema?
Organizational wide view of the data/entire database.
What is the internal level of a schema?
Describes how data is stored and accessed (record layouts, definitions, addresses, etc.).
What are the 3 DBMS languages discussed in the book?
DDL (data definition language)
DML (data manipulation language)
DQL (data query language).
What does DDL stand for and what is it?
Data Definition Language
= builds data dictionary, creates database, describes subschema, specifies security constraints.
What does DML stand for and what is it?
Data Manipulation Language
= changes content in the database; add, delete, manipulate.
What does DQL stand for and what is it?
Data Query Language
= enables retrieval, sorting, display of data from database (eg. SQL).
What is a relational database?
Data model representing conceptual & external level schema as if in a table.
What is the formal name for a row?
What is the formal name for a table?
What is the formal name for a column?
What is an entity?
Subject to which we store attributes.
What is a primary key?
(Combination of) Attribute that uniquely identifies a specific record.
What is a foreign key?
Attribute in one table that is primary key in another (links those tables).
What are the 3 database design errors discussed in the book?
- Update anomaly (changes not correctly recorded)
- Insert anomaly (unable to add data)
- Delete anomaly (unintended consequences of removal of data).
Name the rules we discussed for designing a database.
1. every comlumn must be single valued (cannot combine two values in one field)
2. primary key must contain data (cannot be null)
3. foreign key must contain same data as as the related primary key
4. all other attributes must identify a characteristic of the table identified by the primary key (must relate to the primary key).
What is normalization?
Process to develop a relational database
One gigantic table with all the data, then broken down into several tables according to relationship (third normal form = 3NF).
What does OLAP stand for and what is it?
Online Analytical Processing
= uses queries to retrieve data according to hypothesized relationships (eg. last month's sales amounts).
What is data minig?
Searching for unhypothesized relationships using sophisticated statistical analysis (eg. customer's buying history, then trying to predict future products)
Why use DBMS?
- safe (?).
What is the average cost of data leakage according to Mr. Lineros?
How did Mr. Lineros describe the cycle of technology?
Trying to resolve a problem in the database is like ...
trying to lower the ocean's water level with a spoon.
What are the 2 types of backup we discussed in class?
- wasteful, time consuming, resource intensive
+ simple and fast to restore data
+ fast creation, less resource intensive
- difficult to restore data
What are the 4 jobs we discussed relating to database management?
1. DB implementor (builds DB system)
2. DB designer (creates the schema)
3. DB application developper (creates application interface)
4. DB administrator (maintains DB = loads data into DB and backs up).
What is an index table?
Connects two unrelated tables by primary/foreign key.