Even though I have intermediate knowledge of SQL, I am taking this course to refresh myself. The explanations are crystal clear, and the topics are well-organized. Overall, I would give this course a 5-star rating.
Thank you for putting this course out for us. I can proudly say that I have never enjoyed querying tables until now. You make it seamless and stuck in my head. I don't have to repeatedly memorize queries, without understanding the underlying concepts. Thank you so much
Thank you so much for putting this online and free for us. I'm learning Data Science and getting started with SQL is really easier with your instruction.
Great teacher, Awesome way of communication, each concept is crystal clear and easy to understand. Love to see more videos from you. Great thing CS50. 💌
Thanks so much! I finally understand, after all these years, how JOIN actually works and all its variants. Love the animated joins. Very nice to see what happens visually. That helped to explain things quite a lot. The query within a query, aka as subqueries or nested queries, was all very interesting as well. Didn't realize you could go so deep and do something like that. You know, multiple nested queries all on one line. Pretty crazy.
2:43 Small correction: they are not called relational databases because tables have relationships between them. Extremely common misconception. They are called relational databases because how they work is based on something called "relational algebra"
In moneyball ERD have two tables players and salaries. relation between table players and table salaries 1.N but some players LIKE Satchel Paige doesnt have matches, i dont get something or its mistake
Can anyone figure out why my query is coming back as incorrect? The prompt for Lesson 1, Question 12 in the DESE set of questions is: "Write a SQL query to find public school districts with above-average per-pupil expenditures and an above-average percentage of teachers rated “exemplary”. Your query should return the districts’ names, along with their per-pupil expenditures and percentage of teachers rated exemplary. Sort the results first by the percentage of teachers rated exemplary (high to low), then by the per-pupil expenditure (high to low)." And here's my query: SELECT "districts"."name", "staff_evaluations"."exemplary", "expenditures"."per_pupil_expenditure" FROM "districts" JOIN "expenditures" ON "expenditures"."district_id" = "districts"."id" JOIN "staff_evaluations" ON "staff_evaluations"."district_id" = "districts"."id" WHERE "staff_evaluations"."exemplary" > ( SELECT AVG("staff_evaluations"."exemplary") FROM "staff_evaluations" ) AND "expenditures"."per_pupil_expenditure" > ( SELECT AVG("expenditures"."per_pupil_expenditure") FROM "expenditures" ) ORDER BY "staff_evaluations"."exemplary" DESC, "expenditures"."per_pupil_expenditure" DESC; Every time I check my answers, CS50 tells me this is wrong but I can't figure out why.
There's no need to Join, a subquery will sack for exactly what data we want Join will search the joined table and which multiple conditions which is inefficient
It is not anywhere close. Nested querying is like using a function inside another function. That's it. Recursion is calling the same function inside that very function.
Even though I have intermediate knowledge of SQL, I am taking this course to refresh myself. The explanations are crystal clear, and the topics are well-organized. Overall, I would give this course a 5-star rating.
Cs50 courses are on another league .
Carter you’re a great teacher.
Thank you all🙏🏽
Thank you for putting this course out for us. I can proudly say that I have never enjoyed querying tables until now. You make it seamless and stuck in my head. I don't have to repeatedly memorize queries, without understanding the underlying concepts. Thank you so much
Thank you so much for putting this online and free for us. I'm learning Data Science and getting started with SQL is really easier with your instruction.
You're a great teacher and communicator Carter. Thank you for doing what you do
Great teacher, Awesome way of communication, each concept is crystal clear and easy to understand.
Love to see more videos from you.
Great thing CS50.
💌
Thanks so much!
I finally understand, after all these years, how JOIN actually works and all its variants. Love the animated joins. Very nice to see what happens visually. That helped to explain things quite a lot.
The query within a query, aka as subqueries or nested queries, was all very interesting as well. Didn't realize you could go so deep and do something like that. You know, multiple nested queries all on one line. Pretty crazy.
Great course, I'm learning so much. Congratulations guys! Carter is a great teacher.
Im grateful for taking this course to learn sql
I am absolutely loving these playlists.
2:43 Small correction: they are not called relational databases because tables have relationships between them. Extremely common misconception. They are called relational databases because how they work is based on something called "relational algebra"
Great explaination and so unique way of teaching it help me so much in university 🥰
great explanation, much thanks for you
This guy talks as well as Malan, very good course
Great! Thanks a lot for this tutorial! 🥰
In moneyball ERD have two tables players and salaries. relation between table players and table salaries 1.N but some players LIKE Satchel Paige doesnt have matches, i dont get something or its mistake
Thank you!
Where can I find the data file?
Where do I take this data bases used in the course?
Hi! there are a link named "set of problem" in each week class when you register in the course in the edx harvardX page
Guys how can i download the software or sqlite shown in this image begginer i wanted to code along with him; your help would be appreciated ❤
Can anyone figure out why my query is coming back as incorrect? The prompt for Lesson 1, Question 12 in the DESE set of questions is:
"Write a SQL query to find public school districts with above-average per-pupil expenditures and an above-average percentage of teachers rated “exemplary”. Your query should return the districts’ names, along with their per-pupil expenditures and percentage of teachers rated exemplary. Sort the results first by the percentage of teachers rated exemplary (high to low), then by the per-pupil expenditure (high to low)."
And here's my query:
SELECT "districts"."name", "staff_evaluations"."exemplary", "expenditures"."per_pupil_expenditure" FROM "districts"
JOIN "expenditures" ON "expenditures"."district_id" = "districts"."id"
JOIN "staff_evaluations" ON "staff_evaluations"."district_id" = "districts"."id"
WHERE "staff_evaluations"."exemplary" > (
SELECT AVG("staff_evaluations"."exemplary")
FROM "staff_evaluations"
) AND "expenditures"."per_pupil_expenditure" > (
SELECT AVG("expenditures"."per_pupil_expenditure")
FROM "expenditures"
)
ORDER BY "staff_evaluations"."exemplary" DESC, "expenditures"."per_pupil_expenditure" DESC;
Every time I check my answers, CS50 tells me this is wrong but I can't figure out why.
Is there any reason why at 1:09:42 , "NULL" did not appear for the presenter?
Bro how can I download software he is using.
@@AryanShetty-z3z VS Code
@mastertoru5531 It is the property of SQLite to not show NULL. Different RDBMS follow different convention.
WEELL WE'RE BBBACK!!!!
Why would we use subqueries if we can use joins instead ???
There's no need to Join, a subquery will sack for exactly what data we want Join will search the joined table and which multiple conditions which is inefficient
thanks ❤
Do you have the solutions for the problem set?
We could help eachother in doing problem sets if you want
Hi!, I would like to know if you made a group to help each other with the problem set
When the problmes will be released?
They are out on the edx platform.
Super
Nested querying feels like recursion somehow...
It is not anywhere close. Nested querying is like using a function inside another function. That's it. Recursion is calling the same function inside that very function.
Say no to struggling with sql
I cant see tables in my longlist when i enter ".tables "it just outputs longlist any solution for that? Thanks!
Make sure you downloaded the file longlist-2.db
@@ericvaish where do we download this file from?
❤
bro just did space, space, space, space ☠
He refers to a woman as they. So progressive of him.
What's going on with Carter? Compared to the first SQL lesson he's like on speed!
@davidjmalan what have you done with him? :)