this channel should be a million-subscriber channel, developers overlooked the importance of the database

in my opinion this video serves two purposes: 1 clear and simple explanation for those who need to learn its subject 2 learn the standard of a high quality video tutorial (for SQL or else), many skilled vbloggers fail at it thanks for posting

It’s crazy that I just learned more in 3 min than I did in 2 weeks of a lecture

Man, this completely saved my day. I was banging my head against this concept until I saw this. Thank you.

It's not my job to judge but I have to say something on this one. Like Jack Williams said below, a lot of people are going to learn more in this 7 minutes than in 2 weeks of lecture. Your order of revelation was perfect (and a whole lot of even well seasoned instructors get this so very wrong). Your simple yet totally accurate graphics were perfect for the task. Your narrative and tone were perfect. Your CSV example and the mention of how that violates several normal forms was perfect because it expressed the problem without making "normal forms" a distraction from the gist of the presentation. This should be "required reading/must watch" for all instructors that want to learn more on the arcane subject of how to make an effective presentation. The title and write up on this video are equally impeccable. Very, very well done Mr. Brumm and truly deserving of the "Database Star" handle. If someone asks me about many-to-many joins, junction tables, or just how to solve such a problem, this video is where I'm going to point them to. BOOK MARKED!

This guy should have a lot more credit for his job. Thanks millions!

You have some serious teaching skill. Keep up the great work! Your video's helped me with a current design I'm working on, involving films. Films often have multiple genre's and genre's can of course be associated with multiple films. This video helped me clearly decide to use a joined table. Thank you!

Its a great example of the greatness of Proper and correct way of lecture.

Thank you for the help. I was stuck with this exact problem and couldn't understand where a certain table came from and then saw they just broke up a many to many relationship. Much appreciated! With distance learning videos like this help out a lot!

This channel is so underrated

Chief you're THE Database Star. Thanks a ton. God bless you.

Thanks you, I had a very hard time understanding why the many-many relationships needed a bridge table and your explanation was very helpful.

YOU MADE MY DAY WITH THIS VIDEO. THANKS SO MUCH! PLEASE, DO NOT STOP!

Awesome. This was exactly what I was looking for!

can't believe this content is for free .. this is even better than paid stuff

your explanation is so simple and so clear

This was a really good explanation, and it really helped me in my examination, so thank you so much!

Best video I have seen on Many to Many relationships. Precise and concise. Thanks a lot.

Excellent. very clear explanation, liked and subscribed.

This guy is the DBMS God.

Thank you for the video. I am grateful for your time and contribution. Kind regards, Akira.

This is very good.

Struggled grasping this until I found your video; thanks.

Thank you for your expaination. Helps me to understand the data duplication.

Holy, this video is just pure gold

Awesome! Best explanation on this topic for me. Thanks.

Oohhh that what my tutor was trying to teach me today. Thanks I now understand

very clear and understandable explanation. greetings from germany

thank you once again. Learnt a lot from your videos

Very helpful. The joining table was the kicker for me :) THX!

So much gold !!! Thank you.

Understood. Thanks for the tutorial.

This is a real good example helped me alot, as I was stuck how to make many-to-many relationship. Thanks greatly appreciated!

Very good explanation, thanks!

This was quite helpful. Thank you :)

thank for your sharing

Very clear explanation, I just created tables students and classes. and I tried to insert data. and try joining the query where is who is taking class 1 and what classes are taking student 1. thanks 🙏🙏

solid af, straight to the point most appreciated !

Thank you for this video. Very nicely explained. Can you please confirm/explain if there is a difference between "Joining Table" or "Look Up Table" or are they the same?

Nice video thank you! Just wanted to mention that as someone who would be new to the database. I would prefer the StudentClass table name as it would be easier for me to find it. I have experience working with big database and often I find myself looking at a new table and then trying to find all the relative ones. Lets say if I am looking at Student table, StudentClass would have been the next table that I find, and then Class is already next.

Thank you I have an exam coming up and this really helps a lot!

Thanks for explaining this way more simply and eloquently than my university materials lol

🌞 Thank you, it is clear as day and now I understand the concept of Many-to-many! Yayyy!

Thanks ! [ fastest way to bring back to my memory data base design I did few decades ago :) ] Γ

A joining table seems a lot like a fact table in the dimensional modelling paradigm. It's populated mostly with foreign keys and (optionally) some measures. Is it correct to think of a fact table as a joining table then?

Thanks so much. Made understanding this so much easier.

Amazing video. It is so simple after watching it. Good luck!

thanks Ben , your explanation is short and full of details 🌹🌹

Very good tutorial....

Great content! Thank you!

Thank you so much, you make all details so clear and easy to follow

Would you be able to let me know: We could use a composite primary key for the joining table. Hence, a composite primary key would be unique by definition right? Thanks Michael

Great content

So are bridge tables helping join Dimension tables or Fact tables? Are there any books that dive deeper into this?

it was really nice the explanation abouth the options of using or not the primary key in the student_class. Ty

Thanks for the tutorial!

thanks for this video. I am now wondering 1. Can I set this "Many-to-Many" relationship up in my Oracle 18.4XE DB and 2. How? Obviously, I am totally new to Oracle and setting up and working with DB's.... Help! Also in what order of classes do I need in order to be proficient in this area of IT?

Thank you. Just what I needed

wow ive benn so confusing on designing db with many to many relationship, thank you for the nice explanation

05:10 I don't understand that part. If I set unique const. for table I should do that for each column right? but now we can't assign same class id for other students or vice versa.. How to prevent create duplicate record for both student and class ids?

This is awesome. Thank you

Great video; simple example 👍

Thanks so much for one of the best Database videos I have ever seen. Thanks for spending the time to make things super explicit through detailed and well-explained examples! I have 1 question though. What do i set as the primary key for my linking table? I am using SQLAlchemy and it requires a primary key on each table. Would it be appropriate to set an index (like 0 1 2 3 4 5...) just to satisfy it, no to use? Thanks in advance!

Thank you for this knowledge. I finally get it.

great explanation

Why tf do teachers ( 5 of my teachers ) not teach this way, thanks for the video life saver

I have a question: in the diagram you created showing the crow's foot notation, there is only one notation mark on each end of any relationship. To my understanding, there are supposed to be two notations on each end at all times. Thank you.

thanks, it helped my a lot

Hey thanks for your invested time! I have a question, is it necessary to use two foreign keys? Or can I use only the student Id as a foreign key inside the class table? Thanks!

Thanks a lot man 🙏 u r awesome I have a question if i may, Sometimes Database is not as simple as just one relationship, For example : What if u have a product and that product has multiple color's and every product with a certain color has multiple sizes, So in this situation the color table has many-to-many with the product, and the size table has many-to-many With the product and color which is confusing, because U cant say product-1 has three sizes because the size depends on the color first, What i mean by that is in the real world its gonna be like this : The PRODUCT-1 with the color RED exists in three sizes XL quantity 5 L quantity 10 M quantity 7. So how is this kinda relationship looks like??? Im sorry i know its a long question But i would really really like to see a video like this because all i could find is just the basics and u cant learn much out of that

What do you prefer? Daaaataaaa or Dayyyta?

Thanks for the video.Love it!

Great Video! I have a doubt. You said while linking the student and class table you can't add more rows (for the same person) as it violates the normalisation constraints. But in the final joining table, you made multiple rows for a single student id. Isn't that a vioalation ?

The explanation is very good, I just have one query, if you just have a list of students and you want to get all the common class of those students...? knowing that in java you don't have the student_class entity

If I were to build tables for an English dictionary, would I define tbl_term to tbl_parts-of-speech as many-to-many and then tbl_parts-of-speech to tbl_definition as many-to-many? Thanks

Great video, thanks! How would you write a SELECT statement to get the list of class names one student was taking? For example, at 5:40 looking at your example, it looks like student Claire is taking three classes (DB01, PH01, WEB02). Any advice on what the select statement would look like when a joining table like this is needed to get ? Thanks again!!

Thank you for posting this video

Thank you!

Great

Hi Ben, nice video, thanks. However I do not understand you say in 0:28 "how to avoid it..." I did not get the idea why we should avoid it. I think it is not possible to avoid it or replace many to many relationship. How did you mean it please explain more. You describe only how to use correctly the bridge table and that is it. What I know we could use also composite key. I think many to many is not possible to avoid fully. It is simply such a type of relationship. Each more advanced DB has its relationship and I think there is no point in getting rid of it. Please have mercy on my understanding, maybe i only do not realize the meaning if english word "avoid". thank you.

Thank you very much

Nice explanation, thanks.

Could you help me understand why the class ID isn't considered a primary key while the student ID is considered a primary ID? Isn't it all perspective? 4:33

What would be the SQL query to generate the student_class bridge table? Something like: SELECT * FROM student CROSS JOIN class?

Great Channel

why can we not store multiple ClassIDs per student? is it because there is no array data type in databases? if string is the only thing we can store is it possible to convert array to string and store that value with an understanding that one will need to convert back from string to array before using it?

Nice vid! One question though. I cannot add any data to my joining table, am i thinking wrong here? :) thanks

Can you elaborate on the the relationship between the entities...like what crow's foot notation you would put between each entity and why. Thank you!

This is amazing, i have a similar relationship like this at work in our project. We have a relationship of contact and contact-list. One problem we get is when we need to fetch all contact lists along with the number of contacts belonging to that list (done using grouping in mongodb aggregation), everything is good except the edge that when the contact-list has no related contacts, the contact-list wont even show up in such a query. Any workarounds?

Hello Ben! Thank you for this video. Could you shed some light on this please: I get the purpose of joining table. However, I'm having trouble wrapping my head around the relationships between (student and student_class) and (class and student_class). Why both of those are one to many?

Great Video

Thanks...This is so helpful

one question: is defining extra columns in a joining table a good database design practice?

subscribed this channel👍🏻

Thank you so much for such a great video. I'm always stuck on these relationship things..!! You earn the sub and like :) And I would like to suggest you that if you grab all the related videos and make a playlist or put a link in the description It's all scattered actually I didn't find this video until KZfaq recommended me while I was watching your one-to-one relationship video.. And also it would be great if you can make same videos on a full project example like by using Entity framework core. Anyway I love your teaching style thank you again..!! :)

How about many to many relationships between 3 tables? 4, 5, n tables?

thank you, GOD BLESS

clear explanation!

Thanks alot for a good video!!

Thanks!