chapter 5

Question 1

how is a non transferrable relationship represented

Answer 1

represented with the diamond on the relationship

Question 2

what does an m to m relationship indicate

Answer 2

it shows that an entity is missing from the model

Question 3

when do 1:1 relationships occur

Answer 3

1: 1 relationships commonly occur when roles are modelled (it is mandatory at one end)
1: 1 relationships occur when some entities represent the various stages in a process (only make a distinction between the 2 entities if there is a business need)

Question 4

what is a redundant relationship

Answer 4

A redundant relationship can be derived from another relationship in the model.

Question 5

what is important to check before resolving a redundant relationship

Answer 5

it is important to read the relationship before concluding that it is a redunddant relationship

Question 6

how to resolve an m to m relationship

Answer 6

(answer template)____and since every attribute must belong to an entity, we need to create a third entity. This entity is called an intersection entity.

Question 7

what is an intersection entity

Answer 7

It is the product of the resolution of a many to many relationship

Question 8

how is the UID for the intersection entity shown as

Answer 8

it is represented by the BARRED RELATIONSHIP

Question 9

what is a barred relationship

Answer 9

it is the relationship that participates in an entity’s unique identifier

Question 10

what is a good way to validate an erd

Answer 10

by doing CRUD analysis

part of checking a datamodel for completeness and accuracy is mmaking sure that all the crud functions specified by the business scenario and the business rules are represented in the ERD

Question 11

what is a function

Answer 11

used to perform calculations on data, modify individual data items, manipulate output for a group of rows, format dates and numbers for display, convert column data types, etc.

Question 12

what are the keywords related to create function

Answer 12

−INPUT, ENTER, LOAD, IMPORT, RECORD, & CREATE

Question 13

keywords related to retrieve function

Answer 13

VIEW, REPORT, BRING UP, PRINT, FIND, READ, & LOOK UP

Question 14

what is an example of create function

Answer 14

“Whenever we get a new customer, we take down basic information (name, address, email) and assign an ID.” (CREATE)

Question 15

what is an example of retrieve function

Answer 15

“We’d like to print out a list of the customers whose account is in arrears.” (RETRIEVE)

Question 16

keywords related to update function

Answer 16

−CHANGE, MODIFY, ALTER, & UPDATE

Question 17

example of update function

Answer 17

“When a customer pays their account, we alter their record by modifying the outstanding balance” (UPDATE)

Question 18

what is an keywords of the delete function

Answer 18

−DISCARD, REMOVE, TRASH, PURGE, & DELETE

Question 19

what is an example of the delete function

Answer 19

“A number of our customers were small businesses that were hit hard by the recession. They went out of business. We deleted them from our current records.” (DELETE)

Question 20

performing crud analysis on your data helps you check for _________and ________

Answer 20

scope and completeness

Question 21

whawt happens when your entites are not touched by the crud function (no business rule does crud operations)

Answer 21

then you may not need the entity in the model