Many to many relationships in MySQL 

Thanks Aaron! I don't even use Planetscale or MySQL, but these videos are honestly the best SQL-DB related content on RU-vid. It really takes a lot of presentation skills to make these videos that informative and entertaining. Keep it up!

Great video! Please, because these videos are related put a part 1, 2, and 3 on the title for future users to find them easily.

There's even more benefits to this that, IMO, make it simply the best option. One is the lack of data duplication in the DB. Since we're doing this in a very normalized and RDBMS-friendly way we're really storing the minimum amount of data to make it work. The JSON method has a ton of repeated data, stored as strings. You might see "dark mode": true for thousands of rows. Another benefit is data integrity. Leveraging the DB to enforce a schema is usually the correct choice. We can't insert a flag that doesn't exist, we can't insert for a user that doesn't exist. With JSON there's nothing stopping garbage data from being inserted, leading to silent bugs. The application then has to enforce the schema... programmatically. "dar mode": true is just a bit too easy to slip by.

PlanetScale is becoming the gold standard of SQL tutorials. Did not see that coming!

RU-vid started recommending me videos with Aaron in the Laravel channel too lol

ive just binged watched almost all your videos , im going to do your course next , thanks for doing this

I really appreciate your videos like this!

Brilliant as always. I'm a big fan of many to many like this, so flexible. But I do also like the json method for some stuff too. Bitwise is just too mathy lol.

Props to the ORMs for abstracting this very important relation.

Your only video that gives me an in-depth understanding of SQL and stuffs. I just wish you can do a full tutorial on MySQL 😊

Is there any downside of not having the `id` column on the lookup table and instead having [`user_id` and `flag_id`] being a primary key?

ORMs get a lot of hate in some circles, but you seem to be a strong advocate for it. Could you make a video about why you should use an ORM?

Linking tables are very useful for course enrolment system (student-course, teacher-course, room-course, .certificate_template-course ..) just to name a few example of many to many relationships. I was always call it a Linking table until I read somewhere that it's called a Bridge table. the same meaning though. Thanks Aaron!

Learned like 7 new things in 15 minutes

Very exhaustive and eloquent. I love these videos. Ps. I used to find sql boring.

One interesting approach to getting the data in an array is using json functionality, ive only ever seen it in drizzle and using postgres, i went through the generated query and its pretty performant plus the database is probably faster at json stuff than my js application

Could you compare the performances among the three approaches?

This is exactly how I would handle this. Great video 👍🏾

We call them junction tables. Good video!

Your videos are consistently amazing Aaron!

Love your videos! Thank you!

Why did you use unique constraints? Why not composed primary key? When would you use a surrogate 'id' column vs composed primary key? Would like your opinion on this ))

why not have (user_id, flag_id) as the primary key?

Thank you Steve

FINALLY THE LAST EPISODE!

I don't understand why you have a separate primary key in `users_flags` - shouldn't that just be the unique combination of user and flag? Also, the flag ID index is also required for a foreign key constraint on flags, not just for indexing flag ID alone.

But why to do that when I can just make a Boolean columns for each flag in the Users table?

Please, make video where you need to track when user had wich flag. Show current flags, or at particular date.

So the options .... 1. Pretty savi , not gonna use it or next year I'll put a cross over my head 2. interesting, useful when you don't know the actual structure or maybe you want json back into your app 3. ORM's way love it, currently what I use, not by choice but that I find it more logical. to have everything separate. Thank you for the serie, I did learn some new stuff in the first 2 videos!

Why are you not using REPLACE in 6:28 instead of on duplicate key

One again great video! My boss says you should never ever create queries from the application. You should always use stored procedures for performance and security reasons. Is there any weight to this argument?

Aaron youre the man

Is there any particular reason not to use a composite primary key on the user_flags table?

Which editor / SQL App is this?

1:26 what program is that?

could the flags table be an enum instead?

I was always told that when you do an EXIST (or NOT EXIST) sub-query, you have to use SELECT 1 instead of SELECT * (for performance reasons). Is that true? or it does not matter at all?

The foreign keys on the intermediate table were missing. 😅

What about using an enum in the "relation table" instead of using a full table for the flags ? For me it has the benefice of searchign them by name instead of using the id, and you can have autocomplete, I lose on having a description though.

What is the name of the software that he used to execute command ?

In your JOINs video, you didn't show your EXPLAINS or schema & you got some details wrong. The IN and EXISTS queries had the same exact execution plan. The JOIN created a temporary table of posts (presumably with > 90,000 views). You described the join as duplicating results bc of the DISTINCT filtering, but I'm just not sure that's true from my tests.

Thumbs up!

My insert statement went from 20 seconds to 2 seconda when writing my own SQL instead of dumb ORM doing the same select 30 times instead of 0 times. A lot of similar problems in other parts of the app. It's really wierd that you suggest using ORMs, given that the rest of stuff you make is excelent quality, ORMs are just not it. DX is awesome, but the performance is atrocious in my case (and many other devs agree).

This video's title needs to be changed so people know that this is part of the feature flag series.

“If you aren’t using an ORM, you should be!” _20 primeagan fanboys are typing_