how to combine the result of one column to another - sql

Question

I am trying to create a student database but i am stuck up the given requirement.
I was given to create 2 tables one with students register number , subjects ans total and another table with student_name , total, rank. i can understand that here we need to use the student name separately and combine it later but the part that got me struck in the student subjects may vary means if student no :1 is having 3 subjects means student no : 2 may have 2 and student no: 3 may have 5 and based on this we have to put ranking order
CREATE TABLE Student
(StudentID int, StudentName varchar(6), Details varchar(1));
INSERT INTO Student
(StudentID, StudentName, Details)
VALUES
(1, 'John', 'X'),
(2, 'Paul', 'X'),
(3, 'George', 'X'),
(4, 'Paul', 'X');
CREATE TABLE Subject
(SubjectID varchar(1), SubjectName varchar(7));
INSERT INTO Subject
(SubjectID, SubjectName)
VALUES
('M', 'Math'),
('E', 'English'),
('H', 'History');
CREATE TABLE Mark
(StudentID int, SubjectID varchar(1), MarkRate int);
INSERT INTO Mark
(StudentID, SubjectID, MarkRate)
VALUES
(1, 'M', 90),
(1, 'E', 100),
(2, 'M', 95),
(2, 'E', 70),
(3, 'E', 95),
(3, 'H', 98),
(4, 'H', 90),
(4, 'E', 100);
I need 2 outputs
1st one is
ID |subjects |marks
----------------------------------------------------------
1 maths 98
1 science 87
1 social 88
2 maths 87
2 english 99
3 maths 96
3 evs 100
3 social 88
3 history 90
and the second table as
NO |name |total|rank
----------------------------------------------------------
1 xxx 123 1
2 yyy 456 2
3 zzz 789 3
I need output like this for n number of entries

Answer 1

1 st one
SELECT
A.StudentID AS [ID],
C.SubjectName AS [subjects],
B.MarkRate AS [marks]
FROM STUDENT A JOIN Mark B ON A.StudentID=B.StudentID JOIN Subject C ON C.SubjectID=B.SubjectID
2nd one
SELECT
A.StudentID AS [NO],
A.StudentName AS [name],
SUM(B.MarkRate) AS [total],
ROW_NUMBER() OVER(ORDER BY SUM(B.MarkRate) DESC) AS [rank]
FROM STUDENT A JOIN Mark B ON A.StudentID=B.StudentID JOIN Subject C ON C.SubjectID=B.SubjectID
GROUP BY A.StudentID,A.StudentName
ORDER BY [total] DESC

Answer 2

select StudentID ,SubjectName ,MarkRate from
#Mark a join #Subject b on a.SubjectID=b.SubjectID
output
StudentID SubjectName MarkRate
1 Math 90
1 English 100
2 Math 95
2 English 70
3 English 95
3 History 98
4 History 90
4 English 100
Second Query
with cte as
(
select a.StudentID,StudentName,sum(MarkRate)MarkRate from #Student a join #Mark B on a.StudentID=b.StudentID
group by a.StudentID,StudentName
)
select *,rank() over( order by MarkRate desc) as rn from cte
output
StudentID StudentName MarkRate rn
3 George 193 1
4 Paul 190 2
1 John 190 2
2 Paul 165 4

Answer 3

To get the Mark list with subject name is simply this :
you need to use JOIN :
SELECT M.StudentId
,SU.SubjectName
,M.MarkRate
FROM Mark M
INNER JOIN Subject SU ON M.SubjectID = SU.SubjectID
To get total marks with ranks you need to use GROUP BY and RANK() function :
SELECT M.StudentId
,ST.StudentName
,SUM(MarkRate) Total
,RANK() OVER(ORDER BY SUM(MarkRate) ) Rank
--,RANK() OVER(ORDER BY SUM(MarkRate) DESC) Rank
FROM Mark M
INNER JOIN Student ST ON M.StudentId = ST.StudentId
GROUP BY M.StudentId
,ST.StudentName

Answer 4

I understand that first query lists the marks of each student
SELECT
m.StudentID as ID,
s.SubjectName as subjects,
m.MarkRate as marks
FROM
Mark m
INNER JOIN Subject s on m.SubjectID = m.SubjectID
ORDER BY
m.StudentID,
s.SubjectName
Second query gives the total mark of Students with their rank.
SELECT
X.StudentID,
X.StudentName,
ROWNUMBER() OVER ( ORDER BY X.TotalMark desc) as Rank
FROM (
SELECT
m.StudentID,
s.StudentName,
sum(m.MarkRate) TotalMark
FROM
Mark m
INNER JOIN Student s on s.StudentID = m.StudentID
GROUP BY
m.StudentID,
s.StudentName
) X
ORDER BY X.TotalMark desc

Answer 5

You can try the following query for both output.
SELECT
Student.StudentID as ID,
[Subject].SubjectName as subjects,
Mark.MarkRate as marks
FROM
Student
INNER JOIN Mark on Student.StudentID = Mark.StudentID
INNER JOIN [Subject] on [Subject].SubjectID = Mark.SubjectID
ORDER BY
Student.StudentID,
SubjectName
Below query for second output. Here as you have said for those who has less mark got Rank 1 otherwise you can put Order By Total Desc in below query for higher marks rank 1.
SELECT ID, StudentName, Total, Row_number() Over (Order BY Total) Ranks FROM(
SELECT Id, StudentName, SUM(marks) as Total FROM (
SELECT
Student.StudentID as ID,
[Subject].SubjectName as subjects,
Mark.MarkRate as marks,
Student.StudentName
FROM
Student
INNER JOIN Mark on Student.StudentID = Mark.StudentID
INNER JOIN [Subject] on [Subject].SubjectID = Mark.SubjectID
)Tot
Group By Id, StudentName
)Ranks