Thanks for your clear no non-sense explanation. These concepts should be relatively easy to grasp, but you would be amazed at how misunderstood foreign keys can be.
ooh man this video was uploading in 2011 when I was 11 years old and now I am watching it on my 5th semester 2020 I was playing on streets that time while you were saving me 9 years later..thanks bro
@@Shaima-zl8uk I don’t even remember writing this comment😂 New update: I work as a software developer now and I updated the stored procedures in DB this morning…nothing you learn will be wasted Shaima Good Luck🔥🙏🏻
Thank you, this was a very thorough and practical explanation. I appreciate how you unified all these concepts in a single lecture. I especially appreciate the explanation of a compound primary keys, as in the Order Line table. I was very confused about those.
This is a very thorough and well thought out explanation. The most helpful lessons on data base concepts come from those like you who use a generic approach.
It is a very good video, absolutely make sense. pp who said something negative, if they know better than this video then, they should do it. why not? thank you very much, sir. I really like it.
Hi bud, thanks for the knowledge, and I was wondering why didn't you use customer_id as your "foreign key " in the ORDER LINE table to connect the two tables? Wouldn't that work at all?
This is pretty helpful, but would be WAY MORE helpful if the text was legible, and I could actually read the content to understand the relationships better. Why only 360p?
I am trying to construct a database of assets. If I try to put portals on a single layout, there are conflicts and the data gets corrupted. There are entries like "dividends" "interest" "gain", etc. and I can't figure out how to relate the files - all goes to show how amateurish I am (but I'll keep at the instruction books).
Create a table called Assets with an assetsID as Primary Key. All the other entries are record fields in the table. Some fields will be numeric of type decimal etc. Planning is important, this is where knowing your software and the use of Entity Relationship Diagrams (ERD) come in handy, especially if you are dealing with multiple tables. Frequently backup your data as insurance from data loss.
can there be two primary keys in a single table ? For example if a table CONTACT contains contact number, contact name, address. Then generally contact number has to be primary key. But what if two different persons use the same contact number ? (like father and son).
A primary key has to be an unique identifier. Therefore, the contact number wouldn't be used as a primary key. Each contact would most likely get a unique number that represents them. For example, I could be Customer ID 40232 and you could be customer ID 40233. By using our primary keys, you would then find out the supporting information such as our contact number, name and address.
You can, it's called a candidate or composite key. But he is breaking second normal form with that partial dependency. Someone on here said he should normalize the Order Line table. He's right.
The ContactID (for example) is created by the DBMS when a record is created (the record number in the table), is auto incremented, a positive integer, and must be unique. Only the software and DBMS needs to know the actual CustomerID. Customer Account Numbers are generated when an account (record) is created and is unique to each contact etc (the bit you need to know and keep handy so you can rant to Customer Services). If you have a Contact table containing the following: contactId (primary key) contactReferenceNumber (contact’s unique reference number) title foreName middleName lastName 1stLineAddress etc Two people can be at the same address as they have different reference numbers and a different contactId in the Contact table. In a father / son situation you could find either Senior or Junior using a lastName search ie. SELECT * FROM contact WHERE (foreName = ‘John’ and lastName = ‘Doe Junior’ and city = ‘NY’) Will find the details of every John Doe Junior in New York unless you refine the search parameters in the WHERE clause. To hit the nail on the head and go straight to the customer's record use something like: SELECT * FROM contact WHERE contactReferenceNumber = 'AB72839494'
You need to have a separate shipping table and a shipping detail table. It will be a little bit more complicated. Order table and Shipping table has a 1-to-many relationship.
First thank you, my good man, for the very informative video nicely done. Also, can you please improve the quality of the video I'm on Verizon Fiber Optic and the quality of the video is not great so it's kinda confusing sometimes when you refer back to something.
Could anyone help me with figuring out how the value of the "line item" field in the order line table would work? How would it start off at "1", then automatically increment by 1 (if more than one type of item is purchased), yet start off at "1" again for the next order?
Technically you can use a timestamp to replace the line item #, when you need to display the order detail items for an order, you sort the related order detail rows by the time stamp, then they will be displayed according to the sequence they were created. If you delete or add new items the ordered of these items will be still correct. Using 1, 2 , 3 as line item number is fine, but delete and update may create a problem in sequencing. I probably will not recommend it.
Thanks for the video, but I couldn't bear watching and listening to it for more than a minute. You need to speak farther away from the microphone, and capture screens with a better resolution to make the text legible (which it isn't at all).
There is one primary key exception that I know of. Unless there has been an upgrade since I finished community college in 2013 Microsoft Access needs a hack to handle a many-many relationship between two indexed tables (ie Table A and Table B). To do this you need to create a link table (LinkTableAB) containing just the primary keys of Table A and Table B. Press the shift key at the same time you select the primary key symbol to create both primary keys in the link table. The link table is not indexed. I don't have Microsoft Access so I am working from memory.
Thanks for your clear no non-sense explanation. These concepts should be relatively easy to grasp, but you would be amazed at how misunderstood foreign keys can be.
gets better after Tables and Primary Keys. Glad I gave it extra 3 minutes of my life and learned something of value!
way better explanation than my professor
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Relational databases concepts, never been more simple! Great video!
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ooh man this video was uploading in 2011 when I was 11 years old
and now I am watching it on my 5th semester 2020
I was playing on streets that time while you were saving me 9 years later..thanks bro
Same ,in 2024🤝😂
@@Shaima-zl8uk I don’t even remember writing this comment😂
New update: I work as a software developer now and I updated the stored procedures in DB this morning…nothing you learn will be wasted Shaima Good Luck🔥🙏🏻
@@asma8150 MashaAllah so nice😍 and good luck for you too❤️❤️❤️
Very good Basic concept tutorial.....Really enjoy this....
This is the clearest explanation I have found thus far of these relationships!
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Hey Minderchen, great job! Keep these short, clear, and detailed videos coming! Helps a lot!
Thank you, this was a very thorough and practical explanation. I appreciate how you unified all these concepts in a single lecture. I especially appreciate the explanation of a compound primary keys, as in the Order Line table. I was very confused about those.
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Nice video mr. Really helpful thank you. Its so funny how ppl hate way to much then actually appreciate.
This is a very thorough and well thought out explanation. The most helpful lessons on data base concepts come from those like you who use a generic approach.
Thank you so much! Despite the distracting clicking sounds, your explanation was way better than the one from my teacher. Thanks!
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very clear and constructive explanation about building a simple relational databse, thank you
Thank you for sharing the concept in lucid manner and keeping it interactive as well.
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I'm making my first steps in databases and it's exactly the explanation I needed.
Thank you so much
very best example for better understanding of keys in practical scenario
thank you very much.....
THIS GUY IS THE BEST HAVE SEEN SO FAR
Excellent! I'm new to this and you did a great job explaining relational databases!
Yay I understand the primary key - foreign key relationship now. Thank you :)
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the most well explained tutorial about Data base I have seen so far. Thank you.
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Great Video. Thanks for making a complex topic so easy to understand.
Thanks for explaining...keep making these videos.
waooo..this is superb and excellent video....4 understand P.K,F.K....ITS a fab
This was helpful. I need to watch it again but the core concepts make sense. Thank you for posting this.
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It is a very good video, absolutely make sense. pp who said something negative, if they know better than this video then, they should do it. why not? thank you very much, sir. I really like it.
Immediately helpful presentation if you are blind and deaf.
Hi bud, thanks for the knowledge, and I was wondering why didn't you use customer_id as your "foreign key " in the ORDER LINE table to connect the two tables? Wouldn't that work at all?
wow....the most crystal clear explanation i've ever seen...thank you...
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Wow, thank you very much for posting this. Very thorough and well paced. 感謝！
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You sounded like a Bond villain, but great job, now I finally understand, my professor sucked :(
Excellent explanation!
So grateful for making this so easily understood.
So is Order ID and Line Item on the ORDER LINE table a 'Composite' Primary Key?? Just that bit confused me..
simpliest way to deliver informaion. Thank you!
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Thank god you're here in this world!!!
I'm having an examination tomorrow while still blank :)
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Aren't you breaking Second Normal Form with that partial dependency between the Order table and the Order Line Table?
Hey Chen, lots of love and respect from Anatolia,
Thanks a lot,
Thanks for the video! It was very informative.
Quick question, though: Can you clarify how will "NULL" apply in this?
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Very, very informative. Thank you!
Great Explanation!
this was good.
do you have more of these things?
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Good explanation and good example, thank you very much.
Definitely helped grasp a better understanding.....Thx
Fantastic >>>> All thanks to you.
GREAT VIDEO...THANKS SO MUCH...LOVE YOUR TEACHING STYLE..KEEP IT UP
thank you so much.. i now have a better understanding
Thanks for your great tutorials,
very informative video and easy to understand!!! thanks a lot..
Very clear and concise. Thanks minder.
Excellent delivery
Great video. Thanks for sharing.
Is it not called a candidate key when you use 2 attributes to identify the rest of the table? I thought primary keys could only use 1 attribute
Awesome video!
Thanks for your great tutorials, really appreciate
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Nice explanation. Much appreciated!
thank you, sir. now i understand what is those. *my teacher just suck. they teach way too complex when i am just new to this.
Wow! I've got this now. That helps a lot. Thank you so much. :)
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Amazingly described!
This is pretty helpful, but would be WAY MORE helpful if the text was legible, and I could actually read the content to understand the relationships better. Why only 360p?
I am trying to construct a database of assets. If I try to put portals on a single layout, there are conflicts and the data gets corrupted. There are entries like "dividends" "interest" "gain", etc. and I can't figure out how to relate the files - all goes to show how amateurish I am (but I'll keep at the instruction books).
Create a table called Assets with an assetsID as Primary Key. All the other entries are record fields in the table. Some fields will be numeric of type decimal etc. Planning is important, this is where knowing your software and the use of Entity Relationship Diagrams (ERD) come in handy, especially if you are dealing with multiple tables. Frequently backup your data as insurance from data loss.
this tutorial is really helpful!
ua-cam.com/video/YI06S-0tAoc/v-deo.html
Very clear. Thanks!
Very good video.
Please, disable the clicking sound next time you're making a video!
+Arnold Hofman full of shit
+Sunel Visser ?
Really?
just456bc Nope
lol
can there be two primary keys in a single table ?
For example if a table CONTACT contains contact number, contact name, address. Then generally contact number has to be primary key. But what if two different persons use the same contact number ? (like father and son).
A primary key has to be an unique identifier. Therefore, the contact number wouldn't be used as a primary key. Each contact would most likely get a unique number that represents them. For example, I could be Customer ID 40232 and you could be customer ID 40233. By using our primary keys, you would then find out the supporting information such as our contact number, name and address.
You can, it's called a candidate or composite key. But he is breaking second normal form with that partial dependency. Someone on here said he should normalize the Order Line table. He's right.
The ContactID (for example) is created by the DBMS when a record is created (the record number in the table), is auto incremented, a positive integer, and must be unique. Only the software and DBMS needs to know the actual CustomerID. Customer Account Numbers are generated when an account (record) is created and is unique to each contact etc (the bit you need to know and keep handy so you can rant to Customer Services).
If you have a Contact table containing the following:
contactId (primary key)
contactReferenceNumber (contact’s unique reference number)
title
foreName
middleName
lastName
1stLineAddress
etc
Two people can be at the same address as they have different reference numbers and a different contactId in the Contact table.
In a father / son situation you could find either Senior or Junior using a lastName search ie.
SELECT * FROM contact WHERE (foreName = ‘John’ and lastName = ‘Doe Junior’ and city = ‘NY’)
Will find the details of every John Doe Junior in New York unless you refine the search parameters in the WHERE clause.
To hit the nail on the head and go straight to the customer's record use something like:
SELECT * FROM contact WHERE contactReferenceNumber = 'AB72839494'
thanx for help me in my class to protect teacher
very good explanation
you keep saying at 6:00 that order id is the foreign key for the order table....i think you mean customer id, no?
Why order and delivery table are separated ? . It is not clear if
you could, for example, have multiple deliveries for an order.
You need to have a separate shipping table and a shipping detail table. It will be a little bit more complicated. Order table and Shipping table has a 1-to-many relationship.
Are these table normalized??
Thanks a lot for this, really informative.
ua-cam.com/video/YI06S-0tAoc/v-deo.html
First thank you, my good man, for the very informative video nicely done.
Also, can you please improve the quality of the video I'm on Verizon Fiber Optic and the quality of the video is not great so it's kinda confusing sometimes when you refer back to something.
ua-cam.com/video/YI06S-0tAoc/v-deo.html
Could anyone help me with figuring out how the value of the "line item" field in the order line table would work? How would it start off at "1", then automatically increment by 1 (if more than one type of item is purchased), yet start off at "1" again for the next order?
Technically you can use a timestamp to replace the line item #, when you need to display the order detail items for an order, you sort the related order detail rows by the time stamp, then they will be displayed according to the sequence they were created. If you delete or add new items the ordered of these items will be still correct. Using 1, 2 , 3 as line item number is fine, but delete and update may create a problem in sequencing. I probably will not recommend it.
That's a great idea. Thank you for your help.
ua-cam.com/video/YI06S-0tAoc/v-deo.html
Very good explanation!
Tosh Ram mosalsal asiya
mosalsal asiya
mosalsal asiya
Dude, spot on!!
Very helpful
thank youuu (y) , merci ,, god bless you :)
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clearly explained.
Thanks for these bro
thank you, very informative.
Thank you
You the man
a good vedio
thank its very usfull
Well done
Thanks for the video, but I couldn't bear watching and listening to it for more than a minute. You need to speak farther away from the microphone, and capture screens with a better resolution to make the text legible (which it isn't at all).
great video, i would just suggest a new mouse
whats up with your mouse?
you saved me!
I used Camtasia.
@05:56 CustomerID or OrderID
brilliant
good video should explain how to do more
thnks
i was confuse...but now i understand ....#PD:
Nice video, but man the mouse clicking sound you used is pretty annoying..lol but other than that great video.
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While I appreciate the making of the video I was not able to get past the first minute because of the clicking.
You cannot have more than one primary key in one table, in your case, you should normalise it first..
Source? Isn't it possible to have a "composite" primary key? Or is that not good practice?
You can have a composite key in a table, but he is breaking second normal form with that partial dependency.
There is one primary key exception that I know of. Unless there has been an upgrade since I finished community college in 2013 Microsoft Access needs a hack to handle a many-many relationship between two indexed tables (ie Table A and Table B). To do this you need to create a link table (LinkTableAB) containing just the primary keys of Table A and Table B. Press the shift key at the same time you select the primary key symbol to create both primary keys in the link table. The link table is not indexed. I don't have Microsoft Access so I am working from memory.