ERDs (1 Viewer)

[taker0]

Do we need to know them? cause i keep looking for them in my textbook and cant find...wahts do they look like? does it have something to do with normalising etc?

also what do ERDs look like??

 

[grendel]

ERDs (Entity Relationship Diagrams) are just schemas. No difference at least in the IPT course

 

[Makro]

See attached. As far as I know this is fairly correct. It's an ERD for my olympics database (one of our assessments).

EDIT: My teacher basically gave me this ERD so it can't be too wrong.

 

[mijoe]

ERD are the same as schematic diagrams. They show relationships between entities in a database.

 

[bazookie]

according to wikipedia it's this:

http://en.wikipedia.org/wiki/Entity-relationship_model

but i've never seen that before =[

are you guys sure it is just a schema?

 

[Makro]

see my attached picture..

 

[bazookie]

yes but look at the website... entity relationship diagram with diamonds and boxes wtf? my teacher told me that we just have to draw schemas for thos questions but my teacher is a drop kick so i wouldn't trust him.

 

[Makro]

The wikipedia page is entirely different. Trust me when I say that ERDs are schemas which look like the picture I attached. I've done countless tests/assignments over the past two years to know that this is true.

 

[cxlxoxk]

The wikipedia page is entirely different. Trust me when I say that ERDs are schemas which look like the picture I attached. I've done countless tests/assignments over the past two years to know that this is true.

Entity-relationship diagrams don't show single entities or single instances of relations. Rather, they show entity sets and relationship sets. Example: a particular song is an entity. The collection of all songs in a database is an entity set.

i found this on the wikipedia page, i think the wikipedia page is the same thing, except just explaining it simpler?

I think what it is saying there is that a ERD/Schema wouldn't show eg. "Chasing Cars" and " Snow Patrol"...it would show "song name" and "artist".

 

[Makro]

if you drew one of them though, you'd be wrong.

 

[xcbx]

In the Heinemann textbook it says "An ERD is a graphical method of identifying the entities and showing the relationship between them. "
Cambridge says "An ERD is one type of schematic diagram. It maps entity types, the relationships between them and the characteristics of the relationships etween entity types."

The attachment that Makro posted looks like the one in the Heinemann textbook so I'd assume that it's correct.

Entity-relationship diagrams don't show single entities or single instances of relations. Rather, they show entity sets and relationship sets. Example: a particular song is an entity. The collection of all songs in a database is an entity set.

I'm not sure this is true since my Cambridge book called the table 'headings' entities. Although I'm not sure how correct those books are >>

I think what it is saying there is that a ERD/Schema wouldn't show eg. "Chasing Cars" and " Snow Patrol"...it would show "song name" and "artist".

^^I agree with that though.

 

[ondroo]

The wikipedia page is entirely different. Trust me when I say that ERDs are schemas which look like the picture I attached. I've done countless tests/assignments over the past two years to know that this is true.

Agreed. for the purposes of this course they r like the picture makro attached.

See the board of studies support document page 30. It has a simple one there (but its actually wrong cause it doesnt show relationships).

 

[fallenstar]

See the board of studies support document page 30. It has a simple one there (but its actually wrong cause it doesnt show relationships).

haah, good work bos.