Entity-Relationship Diagrams
Вставка
- Опубліковано 27 тра 2014
- Puzzled over how to make an entity-relationship diagram? This quick video shows you how.
This lecture is only one of fifty on Seventh Morning's "Fundamentals of Business Analysis" course.
Check it out here... This link discounts the course down to $99, but it's only available for the first 500 subscribers...
www.udemy.com/businessanalysi...
Who else came here from the "SQL for Data Sciene" course. Week 1, additional studies.
Meee😊
@@geraldineorieoma7169 That's nice, good luck with the studies 😊
what you guys doing now ! I just started studying
SOOOOOOOO helpful! You sir just summed up an entire chapter of my textbook in less than 9 minutes.
+John Hurley Awesome. Glad it's helpful!
@@NorwalkAberdeen can you help me
If only there were more quality videos on UA-cam like this! Well paced, easy to understand and well narrated.
David, thanks for your kind words!
@@NorwalkAberdeen make more tutorial vids please
They should just play this in my lectures at university! It would have saved them 2 hours of us all wanting to fall to sleep. Thank you for explaining this in an easier-to-understand and not-so-boring way.
THANK YOU!!!! Finally a video that makes sense and properly explains an entity-relationship diagram! Very well done!
It's amazing how a clear voice spoken in neutral english can make all the difference. Given all unintelligible indian tutorials about this that I had to skip before getting to (and staying with) this one.
Yes i wish there was a filter for dialects
here's some voice conversion software: github.com/andabi/deep-voice-conversion
Completely newbie here! Although it looks very complex, analogy is very simple. Everything makes sense right now. Thank you for your time!
I'm late to the party on this, but a great instructional video on UA-cam always deserves praise! Thanks a ton!
Crazy how I found this video before following Coursera's recommendation to this video! I will binge watch the rest of this!
exactly what i needed to hear and see to make things simpler. thanks for everything
so much better and well-explained than my databases professor. thanks for making this video, appreciate it! :)
LOL, yeah, Don has a good nerd laugh. Glad you like it.
The video was very simple, clear and easy to understand. Great Job!!
OMG, I took ER Diagrams from 2 years at college and I used to hate them so much. However, I started to refresh about them because of SQL and well ah I love them now. Strange how people from different parts of the world can have the same Experience! Thank you buddy for the Great Explanation!
Kudos on explaining an actual ER diagram instead of those confusing data model lookalikes most people choose (which are less abstract, and a lot of people prefer that, but easily lead to mistakes).
I personally prefer listing attributes separately, beneath the ER diagram, to make it cleaner since ER is mostly about relationships and because attributes aren't really crucial for the ER part.
p.s. I also hated these (on my first year), but on my fourth year when I got a serious db project, I finally understood them and started to love, well... appreciate, them.
+slothc Appreciation is good enough :) Regarding the attributes being listed separately, I wouldn't disagree with you. Especially because in the real world, the list of attributes can be enormous and muck up the visual model. Thanks for the kudos!
amazingly intuitive and simple to follow. Thank you. You are an extraordinary teacher.
Very clear and concise explanation, thank you!!
Thank you so much! This was exactly what I needed!
This was so useful, I'll never be the first one to say it but going around you-tube looking for technical minded videos can be a nightmare even when the videos really are there with the best of intent.
The explanations were clear and simple,each slide was nicely separated so it never felt as though there was too much going on at any one point the voice over that was giving the explanation of the video was clear, engaged and associable *when I say this, I'm criticizing the countless videos that go on with dry, highly scripted lines that just feel abominable to listen to without breaking your own sanity(
Great! Glad it's helpful!
i finally understand these THANK YOU
This is soo helpful, hoping you make your videos. Your explanation is just very easy to understand
Much liked your method in actually identifying the Cardinality. Thanks : )
Thats a very helpful explanation. Thanks so much!
great tutorial man, kudos!
Thank you! It was very informative and easy to understand.
Thank you sir, This video made me understand what my prof tried to explain.
Simple and great explanation. Thanks
I dont even know how i made it to this video but i just learned something. Great info
I want to thank you a lot for this explanation.
Clear and concise. Thank you sir!
Great video. This explains a lot.
you saved my day ...brilliant
@Louise cris -- UA-cam won't let me reply to your comment! Grr!
In short, these diagrams are put together long before we start to worry about IDs and keys. We would start to use those concepts when creating a logical (or even physical) data model.
Explained in the simplest way, glad I found your video for ER diagrams.
Thank you so much. You have made it so easy to understand.
Sweet video hopefully it will make my pass my database exam :)
Good luck!
Awesome. I was pretty confused in lecture about the ER Diagram. Great video.
Great! Thanks for the feedback. :)
Many thanks, it helped me alot :)
Life saving :) much thanks
Wow thanks for the easy explanation !
I spent one hour to see some one good
But you are fantastic 🤩
Thx a lot it helps me ❤️
Very helpful for A level, thank you
Excellent, thank you!
Great Video.... So helpful....Thanks.................Seventh Morning LLC
5:37 That Laugh LOOOOOL!! its a great video though, Really helped. Thumbs up
Simply amazing!
Superb video, thank you so much.
Thank you, dear author, you literally saved my life!
Ne za chto!
OK, you have to explain as this sounds like an amazing story.... or did you just use literally incorrectly?
Thank you very much sir, you really helped me on my assignment.
Good video, thanks.
I got so curious from the comments I had to skip forward to hear the laugh before I could concentrate lol.
Me too lol
Thank you sir very imformative and clearly explained the symbols
Thank you! I got over the hate significantly after watching this video😇
easily understood .. thanks sir
This is really good, I'm surprise on the low number of videos
"I actually used to hate these"😂😂
Really helpful , thank you
not bad this sums up my first week in 9 minutes
MY 9minits not wasted
Thank you!!
Anyone else here from the Coursera link?
This is a great video!
i have an entity (staff). each of the staff members are managed by zero or one staff members, except Jane Thomas who does not have a manager. The staff members may manage zero or more staff members. Attributes for the staff are (ID, Names, Sex and Age)
it was very good sir...thanks...
Thank you!
Oh my LORD, my teacher taught this badly
Good job!
Chen style takes u- a lot of diagram space by having attributes in individual ovals, and relationships in diamonds instead of just plain lines.
That is true, and they can give the impression that the relationships are entities rather than just descriptors. Couple things to watch out for.
im having trouble with the n and m what side do i use wich
you make me love them , thx bro ^_^
Awesome!
thanks brother! Plain english is VERY helpful. BTW anyone ever tell you you sound like topher grace (eric from that 70's show)!
Glad it's helpful! And ha, no, I've never heard that until now :)
merci beacoup de votre explication claire monsieur.
very nice video. thank you for the recomendations from learn sql from data science coursera course
i have followe you explanation but may you please clarify on how to list assumptions and how to write a data documentation for the ER diagram
what about the unique identifier or primary key of each entity?
if I understand it correctly, in the diagram at 8:00 I thnk there is a typo in the relation "has", a course has multiple lectures (it can participate in multiple "has" reln instance)
but a lecture belongs to 1 course, (a lecture can be seen at most one reln instance in the "has" reln set). so, the connection labels 1 and n are not in the correct places, they should be replaced.
4:55 still confuses me, I mean, can we just use 'm' for both sides? Cause it still means multiple, right?
I'm coming from a Maths background, so bare in mind I'm new to this and could be wrong. However, in Maths it would be convention to label them differently due to them being different sets. You could have a different number of courses and users, but still have multiple of each. Therefore we are clarifying that these numbers can be different, where as if we just had both of them as M, there could be an implication that they are the same number.
Thank you!!!
very helpful
Thanks :)
that soundtrack at the beginning woke me up
Small correction: since each course can have a varying number of lectures i.e. Kn, then under the "Lecture" entity box instead of n it should say Kn, and to the left of the "Lecture" entity box instead of n it should say (n x Kn) - since every user can watch a maximum of all the lectures in the n courses.
I know it's an old video, but does anyone know how to show a foreign key in chen notation
Thanks !
What about Mandatory and Optional relationships?
How many database tables do you need if you have an ER diagram of: user studies course? Do I only have a user and course table with their attributes, or do I need a 3rd table called study?
+meesie1 hello friend, I'm studying computer science probably just as you and what we do is we have 3 tables for an entity - relationship - entity it is a little expensive in the database however this system is used to know exactly what could be the worst scenario for our database if we use a relational system and how much memory we need to assign to the database
Sorry - missed your question somehow!
Just like Jean said, there is a third table.
In this case, it might be called UserCourseMappings or something similar. And the mapping table just contains a column for the UserId and a column for the CourseId. Together those two columns comprise a composite primary key. I believe that's the most common practice. This third table also could be used if you have attributes of the relationship itself (just make additional columns in the mappings table).
Thanks a lot
Which geomatric shape is used to represent entity relationship in er diargram ?????
I have this shit on school, thanks for making things clear. Still very much in period of hating these tho :p
I was from biology, physics, chemistry and math group in my school. I took the Information Technology course in university. No one explained this ER diagram very well and I used to hate it. I agree with this coach. I now understand it better. Thanks for the good video.
Which books should I read to gain this kind of knowledge.
Thank You
Thank you
"And we connect them to whatever Entity or Attribute they are an Attribute of"
Uhh.. Did you mean Relationship? I'm taking notes so i wanted to get everything right..
thank you
Thanks
What are primary and foreign keys?
coursera course brought me here UC Davis spec on SQL
thanx alot
@ 2:50- wasn't that an example of many-to-one? many-to-one isn't listed among the types of cardinality. Can someone please help me understand this part better?
thanks
good video should redo the voice when not having a cold, jea im subscribed very good content .