I have 3 mysql tables:
Client_courses
Client_courses_id Client_id Course_id
1 1 2
2 1 3
3 2 1
Client
Client_id Name
1 Tom
2 John
Courses
Course_id Name Price
1 Microsofr 100
2 Programming 250
3 Leadership 300
I need to calculate how much every client spent money on courses. For example: Tom spent 550 (250+300), John spent 100. And I am confused how to do it.
SELECT SUM(c.Price), cl.Name
FROM Client cl
INNER JOIN Client_courses clc ON cl.Client_id=clc.Client_id
INNER JOIN Courses cs ON clc.Course_id=cs.Course_id
GROUP BY cl.Name
Related
Below are the given tables:
`student` `subject`
------------------- -------------------
id name id subject
------------------- -------------------
1 Alice 1 Maths
2 Bob 2 Science
3 Eve 3 Economics
------------------- -------------------
`marks`
-----------------------------------------------------
id student_id subject_id marks
-----------------------------------------------------
1 1 1 30
2 1 2 40
3 2 3 50
4 3 1 60
5 3 2 70
-----------------------------------------------------
I need an output which should look like below:
`o/p`
----------------------------------------------
name subject marks
----------------------------------------------
Alice Maths 30
Alice Science 10
Alice Economics NULL
Bob Maths NULL
Bob Science NULL
Bob Economics 50
Eve Maths 60
Eve Science 70
Eve Economics NULL
----------------------------------------------
Please note that I am targeting MySQL 5.6.x syntax and I have created a SQL fiddle of above here to ease access to the question.
Here you go
select
st.name,
su.subject,
m.marks
from student as st
cross join subject as su
left join marks as m on m.student_id=st.id and m.subject_id=su.id
order by st.name, su.subject
SELECT student.name,
subject.subject,
marks.marks
FROM student
JOIN subject ON student.id = subject.id
JOIN marks ON student.id = marks.id
ORDER BY student.name,
subject.subject
If I have a "SALES" table, with columns of SaleID, Product#, and CustomerName. and a PRODUCTS table with two columns product_ID and Name. The contains 5 differnt products. In the SALES table populates when a sale is made.
How would I query customer_name with only Product_ID of 1 and 2?
sales table
SALES_ID PRODUCT_ID CUSTOMER_NAME
1 1 DAVE
2 2 DAVE
3 3 DAVE
4 1 TOM
5 2 TOM
6 1 JANE
7 1 MIKE
8 1 MIKE
9 3 MIKE
10 4 MARY
I would like a table result to be
SALES_ID PRODUCT_ID CUSTOMER_NAME
1 1 TOM
2 2 TOM
Select s.CustomerName from SALES s
INNER JOIN PRODUCTS p ON s.Product#=p.Product#
WHERE p.Product# =1
INTERSECT
Select s.CustomerName from SALES s
INNER JOIN PRODUCTS p ON s.Product#=p.Product#
WHERE p.Product# =2
Say I have the following tables,
lesson
id description
-----------------
1 science
2 english
3 maths
lesson_student_rel
lesson_id student_id
----------------------
1 1
1 2
1 3
2 1
3 1
3 3
lesson_tutor_rel
lesson_id tutor_id
--------------------
1 1
2 1
2 2
lesson_assistant_rel
lesson_id assistant_id
------------------------
1 1
1 2
3 2
I would like to count the total number of students, tutors and assistants for each lesson so I get a result like,
lesson_id student_count tutor_count assistant_count
---------------------------------------------------------
1 3 1 2
2 1 2 0
3 2 0 1
I think I've been looking at this too long now and have got completely stuck, I've found a few similar questions but nothing that seems to answer this. Is it possible to do with one query? Any pointers would be good - an answer would be amazing.
Thanks!
I think this does it for you:
SELECT l.id,COUNT(DISTINCT lsr.student_id) student_count,COUNT(DISTINCT ltr.tutor_id) tutor_count
,COUNT(DISTINCT lar.assistant_id) assistant_count
FROM lesson l
LEFT JOIN lesson_student_rel lsr ON lsr.lesson_id=l.id
LEFT JOIN lesson_tutor_rel ltr ON ltr.lesson_id=l.id
LEFT JOIN lesson_assistant_rel lar ON lar.lesson_id=l.id
GROUP BY l.id
I have three tables:
Students
-------------------------------------------------------------
studentId first last gender weight
-------------------------------------------------------------
1 John Doe m 185
2 John Doe2 m 130
3 John Doe3 m 250
Lifts
-------------------
liftId name
-------------------
1 Bench Press
2 Power Clean
3 Parallel Squat
4 Deadlift
5 Shoulder Press
StudentLifts
------------------------------------------------
studentLiftId studentId liftId weight
------------------------------------------------
1 1 1 185
2 2 3 130
3 3 1 190
4 1 2 120
5 2 1 155
6 3 2 145
7 1 1 135
8 1 1 205
9 2 3 200
10 1 3 150
11 2 2 110
12 3 3 250
I would like to have four top lists:
Bench Press
Parallel Squat
Power Clean
Total of the above 3
I can successfully grab a top list for each specific lift using the following query:
SELECT s.studentId, s.first, s.last, s.gender, s.weight, l.name, sl.weight
FROM Students s
LEFT JOIN (
SELECT *
FROM StudentLifts
ORDER BY weight DESC
) sl ON sl.studentId = s.studentId
LEFT JOIN Lifts l ON l.liftId = sl.liftId
WHERE l.name = 'Bench Press'
AND s.gender = 'm'
AND s.weight > 170
GROUP BY s.studentId
ORDER BY sl.weight DESC
However, I am stuck on how to add the highest total of each lift for each student. How can I first find the highest total for each student in each lift, and then add them up to get a total of all three lifts?
Edit
The result set that I am looking for would be something like:
-------------------------------------------------
studentId first last weight
-------------------------------------------------
3 John Doe3 585
1 John Doe 475
2 John Doe2 465
I also forgot to mention that I would actually like two lists, one for students above 170 and one for students below 170.
SELECT -- join student a total weight to the student table
A.studentId,
A.first,
A.last,
C.totalWeight
FROM
Student A,
(
SELECT -- for each studet add the max weights
sum(B.maxWeight) as totalWeight,
B.studentID
FROM (
SELECT -- for each (student,lift) select the max weight
max(weight) as maxWeight,
studentId,
liftID
FROM
StudentLifts
GROUP BY
studentId,
liftID
) B
GROUP BY
studentId
) C
WHERE
A.studentID = C.studentId
-- AND A.weight >= 170
-- AND A.weight < 170
-- pick one here to generate on of the two lists.
I am trying to write a mysql query to return the top 3 courses that have the highest average course rating. I have two tables, Ratings and Courses.
The Ratings table:
courseId rating
1 6
2 2
1 4
2 5
3 3
4 0
6 0
The Courses Table:
courseId cnum cname
1 100 name1
2 112 name2
3 230 name3
4 319 name4
5 122 name5
6 320 name6
I need to return the top 3 courses that have the highest average rating. Any ideas how I could do this? Thanks
SELECT Courses.*
FROM Courses NATURAL JOIN (
SELECT courseId, AVG(rating) avg_rating
FROM Ratings
GROUP BY courseId
ORDER BY avg_rating DESC
LIMIT 3
) t
See it on sqlfiddle.