Test 1 Flashcards
What is a data field?
Information that describes a person, event or thing in a database.
What are other names for a data field?
Attribute, column or simple field
What is a database record?
Database record stores all of the information about an entity
What is an example of a database record?
One employee in a payroll file or one customer is a customer file
What is a database file?
Set of common records form a file or a table
What does a database file contain?
Contains a set of related records. e.g set of customer records or inventory records
What is a master file?
A master file is a database file that stores permanent information e.g part numbers
What is a transaction file
A transaction file is a database file that stores transient information. e.g inventory disbursement & replenishments
What is a database?
Collection of tables that contain all information needed for an accounting application. Several tables create a complete database
What are the two database keys
Primary Key & Foreign key
What is a primary key
Data field in each record that uniquely distinguishes one record from another in a database table.
What is the importance of a primary key?
It is required in every record of a database as a unique identifier
What is a foreign key?
Data fields that enable reference between records in other tables by matching the primary key of the related table
What is a key characteristic of a primary key
It must be unique
What is a key characteristic of a foreign key?
That the they match the primary key of the related table
What do foreign keys allow?
Foreign keys enable a database system to combine information from both tables to produce a report.
What is a data dictionary?
A critical component of a database document that describes the data fields in each database record
How do data dictionaries help with audit?
Establishing an audit trail as it helps to trace data paths in the new system.
Helps when investigating internal controls
What is the basic assumption about the REA model?
That business EVENTS affect firm RESOURCES and involve AGENTS
What is the first step to designing an REA model?
Identify business & economic events
What does REA stand for?
Resources, Events & Agents
What occurs during the Identify business & economic events stage of the REA model design?
Designer will try to record all events that are relevant for management decision making in the database, whether business or economic
What is a business event
An event that does not affect financial statements but can affect important aspects of the organisation. e.g hiring a new CEO
What is an economic event?
An event that typically affects an organisation financial statements. e.g sale on account
What is the second step of designing an REA model?
Identify Entities
What are the two entities related to designing an REA model?
Internal agents
External agents
What are agents?
Agents are the “who” associated with events. Are either internal or external
What are Internal agents?
Agents that work within the firm for which the database is designed
What are external agents?
Agents outside of the firm. E.g a customer
What occurs during the second stage of designing an REA model “Identify Entities”
Identify the AGENTS and RESOURCES
What are resources within an REA model?
Resources represent things of economic value. - anything under the firm’s control, that provides value and of which there is limited quantity
What are common examples of resources within an REA model?
Cash
Equipment
Inventory
Plant facilities
What is the link between events and resources?
Events use, change, transfer or generate resources
How does an REA model help build a database?
An REA model helps to identify database entities because each resource event & agent represents an entity in a relational database.
What are common examples of events
Sales
Purchases
Received goods
Hire an employee
What are common examples of external agents?
Customers
Vendors
What are common examples of internal agents?
Employee
Manager
What is the 3rd step in designing an REA model?
Identify Relationships
What are the two types of relationships in an REA model?
Direct relationship
Indirect relationship
What is the importance of relationships in a database?
Relationships between entities determine the ability to create reports from data. Reports can combine data from linked entities.
What entities have direct relationship in an REA model?
Events typically have a direct relationship with resources agents, and other events.
What entities have an indirect relationship in an REA model?
Resources and Agents are indirectly linked through an event.
What are cardinalities?
Describe how entities are related to each other and refers to the maximum number of one entity that can occur given its relationship to another entity
What are the three cardinality relationships?
one-to-one
one-to-many
many-to-many
What is a common point about cardinalities regarding agents and events?
one-to-many relationship
Events involve single agents, but agents are involved in events many times.
What is the 4th step in designing an REA model?
Create entity relationship diagrams
What are entity relationship diagrams used for?
To depict entities & their relationships
What is the 5th step in designing an REA model?
Identify attributes of entitles
What occurs during the 5th step of designing an REA model “Identify attributes of entitles”
Entitles identified become tables in a database
How do you use the entities to create tables in a database?
Entities have characteristics or attributes that describe them & that data with a table is based on the attributes of the entity
What is important about attributes with an entity table in a database?
Each attribute should only describe one entity & that entity only.
What is the 6th step in designing an REA model?
Convert the E-R diagrams into database tables
What are the 5 basic rules for table creation?
- Every table has a unique name
- Every row is unique
- Attributes in tables have unique names
- The order of the columns and rows is irrelevant
- Each relation has a set of identifiers called keys
What is normalisation?
The methodology for ensuring that attributes are stored in the most appropriate tables & that the database promotes accurate & non redundant storage of data.
What is a consequence of normalisation
Can result in the creation of more tables
What are the steps of Normalisation?
First Normal form
Second normal form
Third normal form
When is a database in first normal form?
All non-key attributes are singular with respect to the key. Meaning that each attribute has only one value.
When is a database in second normal form?
When in first normal form & all attributes in each records depend entirely on the record primary key
When is a database in third normal form?
When in second normal form & all non-key attributes are independent. Meaning that no record contains any data fields where data field A determines data field B
What occurs if a database is not in normal form/
Insert anomaly
Delete anomaly
Update anomaly
What is insert anomaly?
When you want to addd a relation but cant
What is delete anomaly?
When you discard one item, you lose something that you still need
Update anomaly
Non-key data is repeated and update is difficult or impossible.
What is an information system?
A system is a set of two or more interrelated components that interact to achieve a goal
What does an information system consist of?
People Procedures Data Software Information technology
What are the 3 important functions of an information system?
- It collects and stores data about activities and transactions.
- It processes data into information that is useful for making decisions.
- It provides adequate controls to safeguard the organization’s assets.
What are issues with accounting information systems?
Data Analytics Big Data Cyber Security Outsourcing and cloud services Hacking and malware
When creating tables, what should you do if the cardinality maximums are many-to many?
If maximums are both “many”
Create new table with two key fields
Add additional data if necessary
When creating tables, what should you do if the cardinality maximums are one-to many?
Primary key of the entity that can be linked to many instances of the other entity becomes a foreign key
When creating tables, what should you do if the cardinality maximums are one-to one?
Initially just add one of the key fields to the other table. Additional rules specify that you’d consider minimum cardinality
What is the 1st basic rule for relational databases?
Primary keys must be unique and cannot be NULL (entity integrity rule)
What is the 2nd basic rule for relational databases?
Foreign keys can be NULL, otherwise must have value of valid primary key being referenced (referential integrity)
What is the 3rd basic rule for relational databases?
Every column (other than foreign keys) must describe a fact about the primary key
What is important about the 3rd relational database?
every column in customer table (name, address, balance, credit limit) is a fact about customer number x; you don’t store information about products in the customer table
What is the 4th basic rule for relational databases?
Every column must be single-valued
cannot have a list of item numbers in a single column
What is the 5th basic rule for relational databases?
Data type must be constant for a column
Example: in every row, the zip code column must be a 5-digit (or 9-digit) number
What is the 6th basic rule for relational databases?
Neither row nor column order is significant
