LU04.S06 - ERM vs. ERD
Prerequisites
- Work type: Peer
- Means of aid: only teaching materials, no use of ai.
- Timeframe: 5 Minutes
- Expected result: A Word/PDF file with an a comparison of the terms ERM vs. ERD.
Task
Compare both terms, ERM and ERD, and describe the purpose of each, and find at least 2 similarities and 2 differences.
ERM
- Description: First step to find the entities and the correlations between them.
- Purpose: Blueprint of the business cases
ERD
- Description:Identification of details, such as data-types, relation-table and the cardinality
- Purpose: construction plan, ready to build up the data-base physically
Similarties
- Both notation methods are used to describe the data-base structure of the business cases
- Entity = rectangle
- Cardinalities: 1:1, 1:n, n:m
- Entities have attributes
Differences:
- Relations:
- ERM: rhomb
- ERD: relalation-table
- ERD: Described in the Crow's foot notation
- Attributes:
- ERM: bubbles above, which are connected with the entity
- ERD: As details in the Entity, including data-type
- ERD: Memory amount is describes within the data-type defintion
Vocabulary
| English | German |
|---|---|
| prerequisite | Grundvoraussetzung |
| given | gegebene, vorausgesetzt |
| blueprint | Entwurf |
Volkan Demir