Best, simplest, easiest to understand relational database and relationships in a nutshell. No other videos come close to this one. Please don't ever take this video down.
I keep wondering why people are asking about composite keys and primary keys. This is a GREAT beginning overview of relational databases and how they work. Unique identifiers pretty much covers those questions.
I have never seen even a professor explained like thise easy human understandable ;anguage. I study in griffith University. But I could not find the way to easyness. But you are exceptional.
Thank you so much for this video. I have been trying to understand how relational databases work and out of all the places I checked this is the only one that started at the beginning and didn't assume I was a computer expert. Thank you so much.
Very well described many thanks, we are currently migrating lotus notes to a relational database and your video sums up incredibly well why we should be doing it.
Oh man, you really cleared that up for me, thank you so much. I couldn't wrap my head around the terminology, but you made the concept clear for me. Thank you!
Correct. You will also sometimes see the notation of having a "regular" line for the "one" side and a line with two lines coming out of it - looking like a "peace" sign without the circle. That is the "many" side. There are other possibilities. RUclips does not allow for links in comments , so I added a link to an image I quickly tossed together which shows more of "Crow's Feet Notation". If you look up "Relational Database Crow's Foot Notation" you will likely find more.
Thank you SO GOD DAMN MUCH friend. I was starting to play with PowerPivot and Table Relationships in Excel and was struggling to get a hold of this concept as I was trying to connect 2 table directly without considering that the new relationship itself would be the hosted by a whole new table! Many many thanks!!
Yo, this was awesome. I'm studying Django with my dad and in the course we're studying there are Relational database concepts, I didn't know them that well, thank you for the help
Thank you very much! Excellent presentation, clear and easy to understand. I've been struggling to understand this concept for ages, but you've put it very nicely in a nutshell.
I wondered about enrollment ID too. Correct me if I'm wrong but I think it's not even needed. Since you could combine classID and studID to be a unique Identifier. So a primary key consisting of 2 foreign keys.
You have the Customer ID once in the Customer table but can have it many times in the Orders table (though it really can be zero, one, or many times). This is a one-to-many relationship.
Great video; really helps me better understand the basics - though I probably should've paid attention during class instead of tuning out, despite how difficult my professor makes it.
Steve Jobs will be teaching a student who uses a Windows computer... Crazy shit huh?! Thanks a million for this truly helpful video! Very explanatory. Just what I needed for my MS Access classes. :)
I feel like it would be more helpful to single out some basic concepts before diving into the example, but overall the video is very well-made and clear. Love it
Hello Computer Guy, I am doing a relational database but I run into a doubt. if I relate CustomerTbl to OrderTbl, and OrderTbl is related to ProductTbl, will the CustomerTbl be automatically related to ProductTbl? Or I will have to manually relate the tables Customer to Product tables? please help me with that
So what is the alternative to this strategy where you have a 3rd database acting as a middleman that represents the relationships between the first two database? Or is this pretty much the best way to do this. Also, what was the "grade" used for?
As I understood it, the 'grade' in the enrolments table represents the main INFORMATION that table gives you and the primary reason that table exists. You could use that table to see who are the high performing students in the school or who requires more attention. It is not fixed to any particular student or class but is focused purely on grades. An alternative to this database would be a hierarchical database or a network database. You could have the year level as the root node. Then you could divide that root node into subject nodes eg. math, english, etc. In this way you would have a single ROOT record that is continuously divided into PARENT and CHILD nodes forming hierarchical patterns and relationships. Each child inheriting certain traits from the parent records above it. The Database in this video shows an example of a different type of database that does NOT depend on hierarchy BUT on relationships instead.
Excellent Relational Database Concepts video. Do you have more videos in same the concept such as Database Tables, Primary Keys, Foreign Keys, and Relationships,Database Design etc. ?
stefanhyltoft I cannot imagine why, but if the same student was enrolled in the same class twice that would lead to problems. Is that even a possibility? I do not think so… and if that is the case your solution would also work. :)
stefanhyltoft Even then it would be a different class ID - the ID is tied to the specific class, not just the class section. Often schools will have things like PSY10120150001 for the first PSY101 class of 2015.
+Prescott Computer Guy I agree with +stefanhyltoft that you could make what is called a concatenated primary key by combining the studentID and classID for the bridge table, but it really comes down to personal preference. The benefit of having a concatenated primary key is that, as you mentioned, it will cause an error if a student enrolls in the same class twice. That is something that we never want to have happen so we enforce that rule with the concatenated primary key. It is better to have an error that you need to code for, and keeping faulty data out, then having the ability to somehow enroll a student in the same class twice.
ok if this is the case then tell me please how do these concepts work in PHP? if we are retrieving classes that a particular student has in PHP look do we have to run another loop inside the loop?
I have a question about the enrollment ID. Is that a unique combination if StudentID/ClassID/Grade to avoid repeats? or is it more like calling each row of the middle database Enrollment1001, Enrollment1002, Enrollment1003, etc.to be able to call each row as needed?
I don't see why you'd need to avoid grade repeats, so probably for tracking every instance of a student being enrolled. The real question is how it's ordered. By student wouldn't make much sense, but if you did it by class then you could assign every class a range of enrollment ids to prevent overcrowding.
Keynote on a Mac. Low end software and it works great for things like this. Did edit some of the timing and the like in post production with ScreenFlow.
I use Apple's Keynote (similar to PowerPoint but, I think, MUCH better for this type of work) and record, edit with a screencasting program called ScreenFlow (which does a lot more than just screen recording). Keynote is free with Macs, ScreenFlow I think is about $100.
You can, but in most scenarios is not practical, even if enrollment id is not required its always usefull to ad an id column for many... many reason, you will understand that later.
Dude I love yah! This finally makes sense! I'm working on my AWS cert the very easy one, Cloud Practitioner. Do you have any vids on that or how can I get in touch for some private teaching. I'm a poor student but with your way of teaching, its win win! Thanks you for the vid and thank you for sharing your knowledge. Please advise...
Do not have any videos specific to Cloud Practitioner and have not used it. Might be able to play with it, though, and see if I can make some videos. Anything in specific you need?
You are basically searching for relevant information and reporting it. Data 1, data 2 + query = result. If you can do van diagram you can do relationship database.
Best explanation I've come across, thank you 13 years in the future.
You are welcome!
9 years later and you're still helping people learn. Thank you.
U mean 11 years later…lol
13 years later
Best, simplest, easiest to understand relational database and relationships in a nutshell.
No other videos come close to this one.
Please don't ever take this video down.
Thanks. No intention to. :)
Well suited for beginners! I am personally starting from ground 0 and this is THE one made any sense to me at all.
Thank you. Appreciate the comment.
Parry Sun Agreed. Now to figure out how to identify a "non-primary" key......
yes I completely agree with you, but I wished that he continued to explain the concept from A-Z.
absolutely brilliant. the only video i have ever watched that has made this topic make sense
Thank you!
only a minute in and this has explained relational databases 10x better than my teacher
I keep wondering why people are asking about composite keys and primary keys. This is a GREAT beginning overview of relational databases and how they work. Unique identifiers pretty much covers those questions.
Thank you for this video. As someone who learns well visually, I think this visualizes the concept clearly for beginners.
I have never seen even a professor explained like thise easy human understandable ;anguage. I study in griffith University. But I could not find the way to easyness. But you are exceptional.
jadav shanker thank you!
@@PrescottComputerGuy u r not dead yet ,😂
damn that was really good, even by 2022 standards. I'm completely new to this field of programming so this was super helpful, thanks a lot!
Thank you so much for this video. I have been trying to understand how relational databases work and out of all the places I checked this is the only one that started at the beginning and didn't assume I was a computer expert. Thank you so much.
Man you absolutely killed this brake down explanation. God bless. Great job.
Thank you for your kind words.
One of the BEST videos that I have seen about RDBs Fundamentals!
And it's really great for visual learners as me )
P.S. I am from UKRAINE.
Very well described many thanks, we are currently migrating lotus notes to a relational database and your video sums up incredibly well why we should be doing it.
brock mcnuggets
Lmfao, the beast in the box , Brock Mcnuggets (Brock Lesnar music hits).
Agreed
Wow!!! you explain 4 classes of database in 5 minutes....Thanks
Wow. 5 years ago this went online. It really inspired me.
Now 10 years ago
Oh man, you really cleared that up for me, thank you so much. I couldn't wrap my head around the terminology, but you made the concept clear for me. Thank you!
Glad it was helpful.
Correct. You will also sometimes see the notation of having a "regular" line for the "one" side and a line with two lines coming out of it - looking like a "peace" sign without the circle. That is the "many" side.
There are other possibilities. RUclips does not allow for links in comments , so I added a link to an image I quickly tossed together which shows more of "Crow's Feet Notation".
If you look up "Relational Database Crow's Foot Notation" you will likely find more.
Thank you SO GOD DAMN MUCH friend. I was starting to play with PowerPivot and Table Relationships in Excel and was struggling to get a hold of this concept as I was trying to connect 2 table directly without considering that the new relationship itself would be the hosted by a whole new table! Many many thanks!!
You are welcome. Glad you found it useful!
Please edit your comment to remove the blasphemy of the holy spirit
Please edit your comment to remove the stupidity.
lytwaytLaz You're not too bright to not defend God
Yo, this was awesome. I'm studying Django with my dad and in the course we're studying there are Relational database concepts, I didn't know them that well, thank you for the help
Thank you very much! Excellent presentation, clear and easy to understand. I've been struggling to understand this concept for ages, but you've put it very nicely in a nutshell.
I wondered about enrollment ID too. Correct me if I'm wrong but I think it's not even needed. Since you could combine classID and studID to be a unique Identifier. So a primary key consisting of 2 foreign keys.
This i call good tutorial. Love you sir
This is still helpful in 2020,
Thank you computer guy
You have the Customer ID once in the Customer table but can have it many times in the Orders table (though it really can be zero, one, or many times). This is a one-to-many relationship.
Great video; really helps me better understand the basics - though I probably should've paid attention during class instead of tuning out, despite how difficult my professor makes it.
Another excellent presentation!
4,700 'likes' is a great accolade! Congratulations, PCG :-)
Thanks.
@@PrescottComputerGuy
is this the same way we can connect many to many tables by use that junction table?
@@norpriest521
Yes -- the "middle" table creates a many-to-many connection between the other two tables.
This one was really made for the beginners
Finally! a good quality simple vid! Keep em coming! Thanks
After watching this nice video I am grateful to know I already make relational databases on excel.
almost 30.000 views...no dislike...that sums it up! thanx man ,great tut
This can actually be the best explaining video I've ever seen about Relational Databases. Thanks for Sharing! 🫶
Steve Jobs will be teaching a student who uses a Windows computer... Crazy shit huh?!
Thanks a million for this truly helpful video! Very explanatory. Just what I needed for my MS Access classes. :)
I love that all the students in the uni are studs.
So when you pull a list out of enrollments, it should display the student and their classes(and grades)?
Very nice intro to database concepts. Exactly what I needed! Thanks
Excellent, so concise and so understandable!
Thanks.
Prescott Computer Guy is officially my tutor🙏
Student to Class is a one-to-many relationship. The Enrollment object creates a many-to-many relationship between students and classes.
if we keep picking one unique thing and relating it to other tables, wont we have an infinite amount of tables? < does that make sense?
Direct to the point, good work
I wish I had watched this tutorial earlier, it took me too much to grasp these concepts at my own.
Very clear explanation and presentation. Thanks.
Clearest explanation I've seen. Well done!
Thanks! Excellent description of one-to-many relationships.
I didn't understand the final part of the video .. did you mean that every record(enrollment) in the enrollments table has its own id ?
Nicely done. Do you have any more tutorials on relational databases, or MS Access? thank.
I feel like it would be more helpful to single out some basic concepts before diving into the example, but overall the video is very well-made and clear. Love it
Still informative in 2019
This video make me understand what relational database is. Thanks
Excellent , brief and crystal clear.
Wow, that was great! May I ask what program you were using to create your presentation?
Hello Computer Guy, I am doing a relational database but I run into a doubt. if I relate CustomerTbl to OrderTbl, and OrderTbl is related to ProductTbl, will the CustomerTbl be automatically related to ProductTbl? Or I will have to manually relate the tables Customer to Product tables? please help me with that
If I understand what you are saying, they will have a similar relation to what my "Students" and "Classes" have in the example I give.
This was amazing and helpful. Thank you!
So what is the alternative to this strategy where you have a 3rd database acting as a middleman that represents the relationships between the first two database? Or is this pretty much the best way to do this. Also, what was the "grade" used for?
As I understood it, the 'grade' in the enrolments table represents the main INFORMATION that table gives you and the primary reason that table exists. You could use that table to see who are the high performing students in the school or who requires more attention. It is not fixed to any particular student or class but is focused purely on grades. An alternative to this database would be a hierarchical database or a network database. You could have the year level as the root node. Then you could divide that root node into subject nodes eg. math, english, etc. In this way you would have a single ROOT record that is continuously divided into PARENT and CHILD nodes forming hierarchical patterns and relationships. Each child inheriting certain traits from the parent records above it. The Database in this video shows an example of a different type of database that does NOT depend on hierarchy BUT on relationships instead.
Excellent Relational Database Concepts video. Do you have more videos in same the concept such as Database Tables, Primary Keys, Foreign Keys, and Relationships,Database Design etc. ?
Great video, very enlightening and to the point, 10/10
Thank you for awesome explanation. Could you please advise me where to look into for learning normalisation in Database. Thanks!
Love the video. It was a great and quick review on what I learned about databases.
You could also make a primary key set out of studentID and classID I guess, instead of making enrollmentID.
stefanhyltoft I cannot imagine why, but if the same student was enrolled in the same class twice that would lead to problems. Is that even a possibility? I do not think so… and if that is the case your solution would also work. :)
Prescott Computer Guy
I guess if they had to take the same course twice cause they didn't pass it could make problems
stefanhyltoft Even then it would be a different class ID - the ID is tied to the specific class, not just the class section. Often schools will have things like PSY10120150001 for the first PSY101 class of 2015.
stefanhyltoft This would break if you wanted to keep track of the semester/year that the course was taken.
+Prescott Computer Guy I agree with +stefanhyltoft that you could make what is called a concatenated primary key by combining the studentID and classID for the bridge table, but it really comes down to personal preference. The benefit of having a concatenated primary key is that, as you mentioned, it will cause an error if a student enrolls in the same class twice. That is something that we never want to have happen so we enforce that rule with the concatenated primary key. It is better to have an error that you need to code for, and keeping faulty data out, then having the ability to somehow enroll a student in the same class twice.
You are sincerely welcome. Glad it helped.
Excellent explanation. Thank you!
That was very useful for my assignment, Thanks a lot mate...
Thank you - clear, concise and simple!
Thank u man you are the best .a am stress free now I'm going to the exam with confidence😀👏
nice and precise video, no extra information and helped me a lot . . . keep it up
This is such an amazing video!!
Thank you!
so the enrollment is the form shown before?? i mean the relations between students and classes??
Wow lovely great tutorial cleared all my doubts thankyou🥰
I'm so dumb. Would you have to do a vlookup in the fat table to drawn in the student and class id and do the headings need to be the same?
This helped a lot. Thank you!
VERY clear, concise and helpful. Thank you!
thank you that was simple and in to the point no time wasted :D
ok if this is the case then tell me please how do these concepts work in PHP? if we are retrieving classes that a particular student has in PHP look do we have to run another loop inside the loop?
I have a question about the enrollment ID. Is that a unique combination if StudentID/ClassID/Grade to avoid repeats? or is it more like calling each row of the middle database Enrollment1001, Enrollment1002, Enrollment1003, etc.to be able to call each row as needed?
I don't see why you'd need to avoid grade repeats, so probably for tracking every instance of a student being enrolled.
The real question is how it's ordered. By student wouldn't make much sense, but if you did it by class then you could assign every class a range of enrollment ids to prevent overcrowding.
What program have you used to make this video ? Not to record the video but to make the tables and animations.
Good video, very useful!
Keynote on a Mac. Low end software and it works great for things like this.
Did edit some of the timing and the like in post production with ScreenFlow.
I have just one question. Are relationships made between entities or attributes?
Thank you - appreciate it.
Watching this in 2022. Still relevant.
2024😅
a really good lesson. Thank you so very much. Which program have you used for making the video??
I use Apple's Keynote (similar to PowerPoint but, I think, MUCH better for this type of work) and record, edit with a screencasting program called ScreenFlow (which does a lot more than just screen recording). Keynote is free with Macs, ScreenFlow I think is about $100.
Can you show us how a one to one, one to many and many to many relationship in a real and concrete table looks? Thank you very much!
Great, concise informational video. Thanks!
Perfectly explained. Thank you.
Very nice basics.
Could have done well with some annotations with common terminology as you highlight the fields. thank you for crow's feet
Nicely done. Very helpful. thanks!
We are adding this "enrollment id" to introduce a primary key in the table, right? Can't we use both a composite primary key?
You can, but in most scenarios is not practical, even if enrollment id is not required its always usefull to ad an id column for many... many reason, you will understand that later.
okay, thanks
Great video and excellently explained.
That's what I was looking for! Any chance you could make a similarly lovely Object Oriented Database video?
Uuugg, why aren't there more videos that explain databases this well? Thanks for making this video!
Dude I love yah! This finally makes sense!
I'm working on my AWS cert the very easy one, Cloud Practitioner.
Do you have any vids on that or how can I get in touch for some private teaching. I'm a poor student but with your way of teaching, its win win!
Thanks you for the vid and thank you for sharing your knowledge.
Please advise...
Do not have any videos specific to Cloud Practitioner and have not used it. Might be able to play with it, though, and see if I can make some videos. Anything in specific you need?
Great job 👍🏼
Thank you, this was not diffult to understand than my teacher in college
Thank you for that great explanation!
Very clear! This helped a lot
Perfect! Just what I needed to understand it!
You are basically searching for relevant information and reporting it. Data 1, data 2 + query = result. If you can do van diagram you can do relationship database.
Good tutorial,,,
Glad you liked it
that was awesome
Sure. Keynote (part of iWork on OS X) and ScreenFlow.
George J. Bladdermyer is the smartest among them and Ralph squid is the richest among them