AIS-Ch.4: Relational Databases and Enterprises

Microsoft Access

-Simple database management system that can be used to run databases for individuals and small firms

Which of the following is a valid primary key for a cash receipt table? A. Cash receipt number B. Receipt amount C. Purchase order number D. Check number

A. Cash receipt number

Which of the following is a correct statement about primary keys? A. The data values of a primary key must be different (i.e., unique). B. A primary is always another table's foreign key. C. A primary cannot be used in another table as a foreign key. D. Most tables in a database may not require primary keys.

A. The data values of a primary key must be different (i.e., unique).

What kind of relationship does a network data model represent? A. Many-to-one relationship B. One-to-one relationship C. Many-to-many relationship D. One-to-many relationship

C. Many-to-many relationship

Which of the following is a correct statement about entity integrity rule? A. The rule is regarding how to use foreign keys. B. The rule is used to verify the type of data values in each table. C. The rule requires each record's primary key cannot be blank (null). D. The rule allows each primary key must be used to link tables.

C. The rule requires each record's primary key cannot be blank (null).

In the hierarchical data model, the mapping from parent to child is: A. 1:1 (one-to-one) B. N:N (many-to-many) C. N:1 (many-to-one) D. 1:N (one-to-many)

D. 1:N (one-to-many)

Which of the following is a BEST primary key for cash disbursement table? A. Purchase order number B. Check number C. Inventory receipt number D. Disbursement voucher number

D. Disbursement voucher number

SQL

Structured Query Language -computer language designed to query data in a relational database, can update database -queries: user can access, read, & report data -DBMS-making physical changeas to the relational database -SELECT statement: used to begin a query

Database

a collection of organized data that allows access, retrieval, and use of data -Used in a business setting often maintain information about various types of objects(raw materials inventory), events(sales transactions), people(customers), and places(retail store) -3 types of data models used: the hierarchical model, the network model, the relational model

Referential integrity rule

the data value for a foreign key must either be null or match one of the data values that already exist in the corresponding table -the data values of a foreign key should have existed in the reference table already

Database administrator

the person responsible for the design, implementation, repair, and security of a firm's database

Cloud computing

the practice of using a network of remote servers hosted on the Internet to store, manage, and process data, rather than a local server or a personal computer. -companies using often share resources and applications

entity integrity rule

the primary key of a table must have data values (cannot be null)

Cloud computing cons

-Ensure data is secure/backed up frequently -Make sure host has some down time/adequate processing speed at all times -client needs to have constant internet connection

Cloud computing pros

-Enterprise systems can quickly scale to taks -don't need to buy more computers due to increasing traffic demands/spikes

Classes

-customers, sales, products, employees -Classes grouped into resources(R), events(E), and agents(A) -Resources: have economic value for the firm -Events: business activities conducted in a firm's daily operations(sales/purchases) -Agents: people participate in business events(customers/salespeople)

Basic Requirements of Tables

1. Entity integrity rule-primary key of table must have data values(cannot be null) 2. Referential integrity rule-the data value for a foreign key must either by null or match one of the data values that already exist in the corresponding table 3. Each attribute must have a unique name 4. Values of specific attribute must be of the same type(alpha or numeric) 5. Each attribute(column) of a record(row) must be single-valued. Forces to create relationship table for many to many relationship 6. All other nonkey attributes must describe a characteristic of the class(table) identified by the primary key

relational data model advantages

1. Flexibility and scalability-handle new information quickly/easily, most popular data model today 2. Simplicity-easy to communicate to users/developers 3. Reduced information redundancy-each piece of data recorded in one place, keeps info. updated

Cons Enterprise System Implementation

1. Integrating various modules within the enterprise system 2. Integrating with external systems(info system of supplier/customer) 3. Integrating with firm's own existing legacy systems 4. Converting data from existing legacy system to enterprise system 5. Getting any big project implemented at a firm(scope creep, cost overruns, time delays)

Microsoft Access Objects

1. Tables 2. Queries 3. Forms 4. Reports 5. Pages 6. Macros 7. Modules

3 constructs in relational database

1. Tables-primary construct, relation for data storage with rows/columns 2. Attributes-columns in the table are fields and represent attributes 3. Records-all specific data values associated with 1 instance

Foreign key

A primary key of one table that appears as an attribute in another table and acts to provide a logical relationship between the two tables

relational data model

A two-dimensional table representation of data; each row represents a unique entity (record) and each column is a field where record attributes are stored. -allows designers/users to identify relationships when database created/later when new info. needed -can be made up as needed

Primary key

An attribute or a combination of attributes that uniquely identifies each row in a relation. -unique identifier of records

Which of the following could be an "event" in REA data models? A. Cash B. Sales C. Customer D. Inventory

B. Sales

Cloud computing: A. can meet computing needs today but is not expected to meet tomorrow's computing needs. B. is Internet-based computing, where shared resources, software, and information are provided to firms on demand. C. takes energy from the sun and clouds. D. requires a firm to make an extensive investment in hardware and software to meet firm needs.

B. is Internet-based computing, where shared resources, software, and information are provided to firms on demand.

A class in a relational database model is defined as: A. characteristics or properties of a table. B. person, place, thing, transaction, or event about which information is stored. C. the sum of a whole. D. being or existence, especially when considered as distinct, independent, or self-contained.

B. person, place, thing, transaction, or event about which information is stored.

Which of the following is a correct statement about foreign keys? A. All foreign keys cannot not be blank (null). B. Most foreign keys should not have any data values. C. A foreign key must be another table's primary key. D. An attribute cannot be a foreign key used in different tables.

C. A foreign key must be another table's primary key.

Advantages of relational data models generally include: A. ease of implementation. B. most reliable. C. low cost. D. reduced information redundancy.

D. reduced information redundancy.

When using Microsoft Access, the main function of "Table" is to: A. retrieve data. B. analyze data. C. report data. D. store data.

D. store data.

Data dictionary

Describes the data fields in each database record-field description, field length, field type(alphanumeric, numeric)

ERP means

Enterprise Resource Planning

Fundamentals of Relational Databases-Entities & attributes

Entities-resources, events, agents Attributes-characteristics, properties, adjectives

In an REA data model, R means _______ , E __________means , and A__________ means .

Resource Event Agent

What is SQL?

Structured Query Language

The SELECT statement in SQL is used to ___________

The SELECT statement is used to begin a query.

Relational data model vs. hierarchical and network data models

While hierarchical and network data models require relationships to be formed at the database creation, relational data models can be made up as needed.

Database Management System (DBMS)

a computer program that creates, modifies, and queries the database -designed to manage a database's storage and retrieval of information

When using SQL, ________ should immediately follow the SELECT statement.

attribute names

Attributes

characteristics, properties, or adjectives describe each class -Attributes for customer: customer ID, customer last name, customer first name, customer address -Attributes for sales: Invoice number, customer ID, date, and product number -Attributes for products: product number, product name, and product price

Enterprise systems

commercialized information systems that integrate and automate business processes across a firm's value chain located within and across organizations -use relational data model as a basis for the information system

Entity

person, place, thing, transaction, or event in which information is stored

Primary Key vs Foreign Key

primary - a field in table used to uniquely identify a table (underlined) foreign - primary key used in second table as look-up field to identify records from the original table

Which of the following is not a valid link between tables? A. Linking Sales Table and Inventory Table B. Linking Purchases Table with Cash Disbursement Table C. Linking Salespeople Table with Customer Table D. Linking Vendor Table with Customer Table

D. Linking Vendor Table with Customer Table