Hey, you're a great teacher, keep going. I love these. Just a note: your notation example (one cardholder to null or one card) implies that it is not possible to have a card without a card-owner (which, logically, makes sense - why would a bank have a card produced if not for a specific owner?), so just note that 10 min. or so into the video, your card 69 should have an owner? So, I would suggest using an example where there is an owner without a card (because maybe he prefers to only transact online... or his card has not been issued yet, etc. whatever the business reason for the situation). If I'm wrong, please let me know! But otherwise - great teaching.
Very good explanation! I have a suggestion for your videos, perhaps you can make multiple videos of the same topic even though you feel like you have covered them completely in one video. This is because 1) oftentimes a good video is hard to find and 2) I often need to watch more videos on the same topic
Wrong? Isn't your example at 9:40 with ID the other way around? -I-------0-I- means a cardholder can have 0 or 1 cards. Consequently, a cardholder_ID (PK) is valid although it is not referenced as a FK in the card table. Instead, -I-0-------I- means the card_ID 69 can exist without an owner, yes? Or is it me? :)
No, he is talking about the connection between tables. AKA the Primary and Foreign keys. His example means a card can exist without a FK referencing a card_holder. It also has to do with Parent and Child. A card_holder is never going to be a child of a card, but a card will be the child of a card_holder. So the only logical way is card_holder (parent)-> card (child). Also, remember these are each their own respective tables. The card table is already going to exist and have a connection to the card_holder table regardless of whether it has a few NULL values instead of FKs. Now if the card table was the Parent, and the card_holder was the child, you would be correct. In that case it would be saying the FK present in card_holders can be NULL. This parent and child relationship is why he makes the tables the way he does. He almost always has the parent on the left and the child on the right.
Hi @CalebTheVideoMaker2, my question is, if modality 0.1 or 0.N then how could be a child table exist without any parent table? Although a parent table might exist without any child table.
Hello everyone! First of all, thank you for these tutorials, Całeb. They are really helpful plus it's fun to watch you :) However, I don't get one thing. In your example of cardholder-I----O-
explaining a complex thing so simply is a quality of a very good teacher .Thank you Caleb.
you are a legend! your videos about cardinality and modality helped me so much. thank you
Old, but Gold. Thank you so much for sharing free valuable contents with us. Your playlist is awesome.
Hey, you're a great teacher, keep going. I love these. Just a note: your notation example (one cardholder to null or one card) implies that it is not possible to have a card without a card-owner (which, logically, makes sense - why would a bank have a card produced if not for a specific owner?), so just note that 10 min. or so into the video, your card 69 should have an owner? So, I would suggest using an example where there is an owner without a card (because maybe he prefers to only transact online... or his card has not been issued yet, etc. whatever the business reason for the situation). If I'm wrong, please let me know! But otherwise - great teaching.
I've struggled with Modality and this has helped me out immensely. Thanks!
Very good explanation! I have a suggestion for your videos, perhaps you can make multiple videos of the same topic even though you feel like you have covered them completely in one video. This is because 1) oftentimes a good video is hard to find and 2) I often need to watch more videos on the same topic
Caleb you are left hander.
thank you caleb! u really helped me with your videos! thumbs up!. i hope you make web development videos
Wrong? Isn't your example at 9:40 with ID the other way around?
-I-------0-I- means a cardholder can have 0 or 1 cards. Consequently, a cardholder_ID (PK) is valid although it is not referenced as a FK in the card table. Instead, -I-0-------I- means the card_ID 69 can exist without an owner, yes? Or is it me? :)
Yeah, I believe you are right
Right.........
No, he is talking about the connection between tables. AKA the Primary and Foreign keys. His example means a card can exist without a FK referencing a card_holder. It also has to do with Parent and Child. A card_holder is never going to be a child of a card, but a card will be the child of a card_holder. So the only logical way is card_holder (parent)-> card (child). Also, remember these are each their own respective tables. The card table is already going to exist and have a connection to the card_holder table regardless of whether it has a few NULL values instead of FKs.
Now if the card table was the Parent, and the card_holder was the child, you would be correct. In that case it would be saying the FK present in card_holders can be NULL. This parent and child relationship is why he makes the tables the way he does. He almost always has the parent on the left and the child on the right.
Thank you! This was something I really struggled to understand, and you just made it seem obvious from the beginning.
Very comprehensive. Thankies fella
Its more easier to understand if we say 0 as O (Optional)
isn't card holder supposed to be | | (one and only one)?
Great video Caleb!
how can I practice it until I get it? do you have some sample tasks pls
Are you saying if a foreign key has modality zero it cannot be defined as NOT NULL ?
Hi @CalebTheVideoMaker2, my question is, if modality 0.1 or 0.N then how could be a child table exist without any parent table? Although a parent table might exist without any child table.
Thank you Caleb for your help! Great video!
why did you say "piss" at the end
Caleb dude you rock!!!!!!!!!!!!!!!!!!!!!
what is optionality
thanks. you're a legend!
Good lesson! Thanks :)
Im wondering how many lessons left :D
Super helpful, thanks so much :)
good and simple video
Thank you my friend
Hello everyone!
First of all, thank you for these tutorials, Całeb. They are really helpful plus it's fun to watch you :)
However, I don't get one thing. In your example of cardholder-I----O-
That chork powder makes me sneeze man.
you are awesome, this really helped :)
I laughed @ 9:56 when you did a double take on doing 69 as an example. Nice.
great video, the chalk hurts my ears though for some reason lol
very helpful thanks a lot :)
can u teach about eerd n erd?
ua-cam.com/video/vmFFEok91GU/v-deo.html
I Also have a lot of videos over MySQL Workbench.
->-0----------------------------|-|-----
can you explain that ??pls
you don't need to be a tech youtuber to say F linus
using 1.5 playing speed to watch this video
SO u r saying one card can have many cardholder or user !!! BRO hOW IS THAT :p I M ON WEED
quienes vienen y que hablan español sjsjsjsjsjsjs
OMG, get on with it -- 5 minutes and you've said nothing