Joins in MySQL | Intermediate MySQL
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- Опубликовано: 6 фев 2025
- Full MySQL Course: www.analystbui...
In this lesson we are going to take a look at Joins in MySQL!
GitHub Code: github.com/Ale...
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All opinions or statements in this video are my own and do not reflect the opinion of the company I work for or have ever worked for
i looked at several videos regarding joins and believe me, your way of explaining the topic is the best.
6 minutes in and I already understand more than an online course I’m enrolled in. Subscribed!!😊
same here
A gold mine of information. So happy I came across this boot camp.
The summary for the outer join is :
○ LEFT JOIN
§ You take everything from the left table , and the matches of the right table
○ RIGHT JOIN
§ You take everything from the right table and the matches of the left table
Glad im in the intermediate now. I doubt I understood everything in Beginner. I will go back and come when I understand 90% of it.
Poor Leslie Knope isn't getting a present this year! 🤣
:(
@@AlexTheAnalyst Why does craig show up in list 2, but not list 1? Is it because Ron isnt on list 1?
What I wanna know is how Leslie is making more money even though Ron is her boss?
@@RMIVfitness I make more than my bosses do. Though I am in a different industry.
@@AlexTheAnalyst 16:29 in here yes the department works fine but still salary employee id = 2 Ron is missing. So the table is missing the rows. So my question is why we didnt do right join in the first join code while joining multiple tables together? So instead of missing it we could have null value on dem table. idk it came to me more logical and feeling sth is wrong and missing infos with this way. @AlexTheAnalyst
Ron Swanson redacting his birthday was a hilarious reference from the show hahaha
Really explained from top to bottom and very precise and accurate in detailing all aspects
I didn't understand anything at first but then it all fell into place.
thank you
After years in a career as sports analyst. I've been looking for ages for a course to learn SQL et al to transition out. I have some knowledge of python, R and tableau from my sports analysis ventures but I just wanted to say thanks for making this so easy to follow and free. It's such a helpful resource when it can be a little overwhelming when trying to figure out where to start.
Done the beginner section in 1 evening, moving onto the intermediate now :)
Hi Alex, thanks for these great introductions. You present great examples that show the essential concepts. There is one topic though that I believe deserves some attention: The differences between the different SQL dialects. For example, If I compare this video to your intermediate SQL video on "Join", then mySQL seems to be missing the "full outer join" option.
been struggling to fuly understand joins for weeks until i stumpled on this boot camp, but in this self join xample i don't think Leslie got herself a secret santa 😂
A hard piece of material, but it was explained in a very gentle manner.
the only SQL video that explains JOIN in plain english) thanks))
Getting ready for an interview! This helped cleared some things up! Thanks!
Thank you so much you are CARRYING my cs degree rn 😭🙏
joins are used to combine rows from two or more tables based on a related column between them. types of joins:
- INNER JOIN: Returns rows with matching values in both tables.
- LEFT JOIN (LEFT OUTER JOIN): Returns all rows from the left table and matched rows from the right table. If no match, returns NULL for right table.
- RIGHT JOIN (RIGHT OUTER JOIN): Similar to LEFT JOIN but returns all rows from the right table.
- FULL OUTER JOIN: Returns rows when there is a match in either table, or NULL when no match exists.
Each join serves different purposes based on the relationships between your data tables.
this was posted on my birthday! thumbs up January babies!
The beginner videos were easy, and I thought I am too good at this, till I reached this video haha. It definitely got harder :D
That's the beauty of SQL - always more to learn!
Thank you, this is so helpful I’m so happy I found this boot camp
Are you in the ALX programme?
@@palesampeExplore AI program
Exactly the information i want, clear and simple...straight to the point.
Great lesson Alex. It's been quite some time since I practiced any sort of JOIN in any flavor of SQL. Great review! Thanks for your outstanding work. Cheers! 🤠
As a huge fan of parks and rec i enjoy learning from these video : )
hello, as an aside from the great info, i have to give it up to you on your attention to detail to the parks and rec canon. not having ron swanson gave me a chuckle. great content, thank you for putting this out there!
Thanks a lot you make learning very easy
thank you for this, loved the beginner series- concise amd clear!
OMG I LIKE THIS SESSION!
It's starts to get wild
Thank you ALEX for all you do.
Love your way teaching
Great job sir 👍
If you don't mind make videos about creating indexes, triggers, auto_increment in mysql
Some of those will be in the advanced series next :)
Alex kindly make a playlist on azure.
Hey I Was Looking For This Video Thanks
Got it done thanks!
Thank you so much, Alex. Awesome lesson
Hello, Done, Thank you so much.
At 10:40 the +1 is added to the left table. But, when we run the query, it looks like the right table was added with one. How exactly does this work?
I found the answer to this. The join condition is emp1.employee_id + 1 = emp2.employee_id. This means that for every row in emp1, SQL will add 1 to the employee_id and then look for a match in emp2 where the employee_id equals this modified value.
@@RogerAmannaThank youu for writing your findings
When adding columns to inner join. You have to specify a table so you put dem. Before the column name. What if you referenced the other table instead and did select sal.employee_id, age, occupation
?
How will this change the resulting table when ran?
Thanks this is great!
Hi sir thanks for this great unforgettable teaching us
In self join, Leslie is not assigned any Santa and Craig does have to buy any present. How to rectify that?
dept_id does not show up when query,
select *
FROM employee_salary
;
But it does show up when query,
select dept_id
FROM employee_salary
;
On thing in my mind is that there is joining of two tables so the employee id column are showing double why should not there is only one employee id column
INNER JOIN: Returns only the rows with matches in both tables.
LEFT JOIN (or LEFT OUTER JOIN): Returns all rows from the left table, and the matching rows from the right table. If there's no match, it shows NULL for the right table's columns.
RIGHT JOIN (or RIGHT OUTER JOIN): Returns all rows from the right table, and the matching rows from the left table. If there's no match, it shows NULL for the left table's columns.
FULL JOIN (or FULL OUTER JOIN): Returns all rows from both tables. Where there's no match, it shows NULL for the missing side.
CROSS JOIN: Returns the Cartesian product of both tables (all possible row combinations).
SELF JOIN: Joins a table with itself.
Sir in 16:49, the last query you wrote, you have added alias names for first two tables but you haven’t added alias name for parks_dept table; instead you wrote as pd. Why ??
pd is alias for parks_dept table ..we can directly write it after table name or can use "AS pd"
yeah seems to be used as a shortcut by skipping "AS" but I added that during my follow through so it makes sense to me
Thank you so much!
Thank you!
Hey can you make a video in how to download a program to practice data. Or is there a way for you to add it into your website for people to practice with data from outside like Jupyter but for sql
in the analyst builder course is it the same as this one or different? thank you for those who will answer :)
As a recruiter yourself Alex what level of skill set are you looking for when you're trying to look for a entry level analyst?
A solid concept up to Intermediate.
Sir should I Start my career in data analytics with python or sql
Thanks Alex
thank you so much Alex the Analyst
lets put it in a logic gate
INNER JOIN: AND GATE, IF ONE OF THE ROWS DOESNT EXIST WHILE THE OTHER DOES, ENTIRE THING GONE!!
FULL OUTER JOIN: EVERYTHING
LEFT OUTER JOIN:" OR gate where everything on the left will output but everything on the right will show NULL and everything on the right will only be shown if there are datas that have the same value as the values of the left
RIGHT OUTER JOIN: VISE VERSA FOR LEFT OUTER JOIN
Sir I have a question..
From where did I get that employee inputs or insights I don't have that
I am simply implementing queries with any output
Can you please help me with that??
Hey, please bring more project based videos.
I always do :)
What Is full outer join?
I've completed all ur videos of this course till yet but didn't understand anything in sql. What the use of these functions in sql?
i just didn't got the point of emp1 and emp2 can anyone explain ?
hello Sir Alex
if I only write
SELECT * FROM employee_demographics;
its bring me Error have to write
SELECT * FROM parks_and_recreation.employee_demographics;
even if am inside demographics table.
He goes over this in the fourth video of this bootcamp (Select Statement in MySQL) but you may have the wrong schema selected in the navigator section on the side, if the parks_and_recreation isn't bolded then the data will not be automatically pulled from that data set. Hopefully this helps and I explained it in a way that makes sense, I'm still new myself so if it's not that then I don't know lol
Easy 😉
Thanks for the lesson, I keep having error problem (1046), how do i resolved it.
Thanks
Nahh. I think Mark got one. No santa for Leslie 😅😂
One problem though, the first employee Leslie doesn't have a secret Santa. I guess no gift for her this Christmas ;)
I have notice something when he is renaming or assigning names, He uses AS sometimes and not in the others, Am I missing somthing?
Pls refer to limit + aliasing inmy sql video....
Can I ask ? during the self join how were you able to write employee_salary emp1 and used it in the ON statement emp1.employee_id without AS?
it is because, in aliasing, you do not necessarily have to write AS. So employee_salary emp1 and employee_salary AS emp1 will be the same. There is a video about this in his Beginner Series
@ thanks
hey Alex do you still have the patreon page ?
awesome...
Sir, you've recommended Udemy and Coursera.... what about Analyst Builder for certification?
I think my courses are a little bit better than what you'll find on Udemy and there are practice questions integrated into the course too which Udemy doesn't have. It does have a Certificate at the end just like Udemy has :)
How much roughly your course fee@@AlexTheAnalyst?
16:29 in here yes the department works fine but still salary employee id = 2 Ron is missing. So the table is missing the rows. So my question is why we didnt do right join in the first join code while joining multiple tables together? So instead of missing it we could have null value on dem table. idk it came to me more logical and feeling sth is wrong and missing infos with this way. @AlexTheAnalyst
Please I need help.. I don’t think I have the data for parks department
Is it alright if I don't get it in the first go?
i can't find 3 dataset files
✅complete
Which version kf SQL is this
where i can download these data
Why are you deleting or hiding videos ?
done
Have you ever Prepared already for Trigger?
“Let’s look at a very serious use case for self-join”…
Proceeds to funding secret santa.
But what’s the real purpose of self-join in a real-world? Why would you want to join a table to itself? Just trying to understand
Honestly, the self join looks complicated to me.
Could you please let us know that can AI replace the data analytics job? I am going to end your course on data analytics but I have heard that soon AI can replace it. Thanks
indians attendence here🎉😂
People just keep producing identical content on RUclips. Quite a waste of time
Don't watch
@alextheanalysist how to get the two outputs in one query table i have tried but not getting the result and it showing database is not connected
can i ask a question in self join you add 1 ON emp1.employee_id + 1 = emp2.employee_id, However the one added to 'emp2.employee_id ' not 'emp1.employee_id ' ?
and another question we apply here self join using inner join , he should return for me only matches emp_id, i mean
2 Leslie Knope 2 Ron Swanson
3 Ron Swanson 3 Tom Haverford
4 Tom Haverford 4 April Ludgate
5 April Ludgate 5 Jerry Gergich
=======================================
like this all over until he finished them why he returned for me like self join using left join like result appear in 13:00
Same question please anybody answer this
JOINS
inner join
->inner join simply joins two database tables based on
->just like AND gate
[
SELECT *
FROM [chemical thermodynamic and polarizability table].[dbo].[Chemical] AS c
INNER JOIN [SQL Tutorial].[dbo].[quantum_research_papers] AS q
ON [SQL Tutorial].[dbo].[quantum_research_papers].categories = [chemical thermodynamic and polarizability table].[dbo].[Chemical].Energy;
]
D1 denotes database 1 and D2 denotes database 2 will “merge” and excliude the databases that either of the tables do not have [simply the inner join] based on the common column name between the two databases tables
Note:
Its best to mention the [DATABASE_NAME].[dbo].[QUERY_NAME].column_name
LEFT JOIN is like OR gate where everything on the left will output but everything on the right will show NULL and everything on the right will only be shown if there are datas that have the same value as the values of the left
VISE VERSA FOR RIGHT JOIN
FULL OUTER JOIN IS EVERYTHING LITERALLY
At what point do you explain about EMP? 🥲
Correct me if i am wrong but this is what i understood ..........................
3 TYPES OF JOINS :
1. INNER JOIN
2. OUTER JOIN [LEFT OUTER JOIN & RIGHT OUTER JOIN]
3. SELF JOIN
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
1. INNER JOIN : RESULT WILL BE THE ONLY VALUES WHICH WILL MATCH IN BOTH TABLE1 & TABLE2 .
2.1 OUTER JOIN [LEFT] : RETURNS ALL THE VALUES FROM LEFT AND RIGHT TABLE , BUT IF THERE ARE ANY MISSING VALUES FROM RIGHT TABLE THEN IT REPRESENTS THEM AS NULL INSTEAD OF DELETING THAT ROW .
2.2 OUTER[RIGHT]: RETURNS ALL THE VALUES FROM RIGHT AND LEFT TABLE , BUT IF THERE ARE ANY MISSING VALUES FROM LEFT TABLE THEN IT REPRESENTS THEM AS NULL INSTEAD OF DELETING THAT ROW .
3. SELF : THE TABLE IS JOINED WITHIN ITSELF [TABLE1, TABLE1 SITUATION ] OR SELF JOINED TABLES 🤔🤔
Thanks Alex