Lets say I have the following table:
Student Course University
1 a x
1 b x
1 c x
1 a y
2 a x
2 a y
2 a z
3 a x
For each student, I am trying to find the number of unique courses and universities that they are enrolled in.
The output would be as follows:
Student No. of Courses No. of Universities
1 3 2
2 1 3
3 1 1
How would I construct the SQL for this?
SELECT Student,
COUNT(DISTINCT Course) AS NumberOfCourses,
COUNT(DISTINCT University) AS NumberOfUniversities
FROM YourTable
GROUP BY Student
Related
Using example below, Day 1 will have 1,3,3 distinct name(s) for A,B,C respectively.
When calculating distinct name(s) for each house on Day 2, data up to Day 2 is used.
When calculating distinct name(s) for each house on Day 3, data up to Day 3 is used.
Can recursive cte be used?
Data:
Day
House
Name
1
A
Jack
1
B
Pop
1
C
Anna
1
C
Dew
1
C
Franco
2
A
Jon
2
B
May
2
C
Anna
3
A
Jon
3
B
Ken
3
C
Dew
3
C
Dew
Result:
Day
House
Distinct names
1
A
1
1
B
1
1
C
3
2
A
2 (jack and jon)
2
B
2
2
C
3
3
A
2 (jack and jon)
3
B
3
3
C
3
Without knowing the need and size of data it'll be hard to give an ideal/optimal solution. Assuming a small dataset needing a quick and dirty way to calculate, just use sub query like this...
SELECT p.[Day]
, p.House
, (SELECT COUNT(DISTINCT([Name]))
FROM #Bing
WHERE [Day]<= p.[Day] AND House = p.House) DistinctNames
FROM #Bing p
GROUP BY [Day], House
ORDER BY 1
There is no need for a recursive CTE. Just mark the first time a name is seen in a house and use a cumulative sum:
select day, house,
sum(sum(case when seqnum = 1 then 1 else 0 end)) over (partition by house order by day) as num_unique_names
from (select t.*,
row_number() over (partition by house, name order by day) as seqnum
from t
) t
group by day, house
I have a table (stu_grades) that stores student data and their grades at the centers they attended
I want to find out how many times for e.g. each student in that table got 'A' and then 'B' etc at any center
stu_grades
stu_ID|grade1|grade2|Grade3|center
1 A A C 1
2 B B B 2
3 C C A 1
1 C A C 2
the same student could occur more than once in the table with the same grades or even a different grade, same or different center
I especially want to check where the grade has appeared more than 3 or more times and how many centeres they exist in
So the final output should be like:
Stu_ID|Grade|Count|centercount
1 A 3 2 (As they accquired 'A' from 2 centres)
1 C 3 2
2 B 3 1 (As they only exist in 1 centre)
3 C 2 1
3 A 1 1
select
stu_id,
grade,
sum(count) count,
count(distinct center) centercount
from (
select stu_id, grade, center, count(*)
from stu_grades,
lateral unnest(array[grade1, grade2, grade3]) grade
group by 1, 2, 3
) s
group by 1, 2
order by 1, 2;
Test it here.
I have two table and have to fill in a list of missing values in one of the table based on the other one. First table has student's information and the second table has Grade related info, Grade and Grade description.
Table One
ID Name yearWithUs Grade Course Level
1 Jim 2004 4 4
2 Jim 2004 4 1
2 Jim 2003 3 3
4 Jim 2002 2 3
4 Jim 2002 2 1
3 Jim 2001 1 2
3 Jim 2001 1 1
Table two -- logic is.. A Student in a higher Course Level can change to a lower Course Level at anytime during the semester. And It can only go downward 1 level at a time. Example: Jim in his second grade first was assigned to attend course in level 3. He need to attend course in level 2 first before he can attend course in level 1. Means. Row for course level 2 at jim's first grade is missing.
Table Two
ID Grade Grade_Desc Course Level Course Desc
1 1 First Grade 1 Basic
2 1 First Grade 2 Normal
3 1 First Grade 3 Hard
4 1 First Grade 4 Expert
5 2 Second Grade 1
6 2 Second Grade 2
7 2 Second Grade 3
8 2 Second Grade 4
. . .
. . .
. . .
Logic of Table Two
ID Grade Grade_Desc Course Level Possible Move
1 1 First Grade 1 Null
2 1 First Grade 2 1
3 1 First Grade 3 2
4 1 First Grade 4 3
Ouptput one ... how to use select statement to return Jim's Grade?
ID Name Grade_Desc Grade yerWithUs Course Level
1 Jim Fourth Grade 4 2004 4
2 Jim Fourth Grade 4 2004 3
3 Jim Fourth Grade 4 2004 2
4 Jim Fourth Grade 4 2004 1
5 Jim Third Grade 3 2003 3
6 Jim Second Grade 2 2002 3
7 Jim Second Grade 2 2002 2
8 Jim Second Grade 2 2002 1
9 Jim First Grade 2 2001 2
10 Jim First Grade 2 2001 1
Output Two..How to retrieve only the missing row into a new temp table?
ID Name Grade_Desc Grade yearWithUs Course Level
2 Jim Fourth Grade 4 2004 3
3 Jim Fourth Grade 4 2004 2
7 Jim Second Grade 2 2002 2
I am currently is using a messy Cursor Statement to do it. The structure looks really messy and hard to debug return errors. I did a lot of research, and saw people use Cross Join to fill the missing portion which looks really clean (See example below)... I have tried the script it myself in many different way by using the cross join example below...obviously, I failed. I found a similar question in stackoverflow..but I am not able to understand how does it work and why without looking at the data....I need help to understand how to use cross join to rerun missing row? and I am open to any other possible solution.
"SELECT calendar.Date,
Category.Cat,
Score = ISNULL(Scores.Score, 0)
FROM Calendar
CROSS JOIN Catogory
LEFT JOIN Scores
ON Scores.Cat = Category.Cat
AND Scores.Date = Calendar.Date
WHERE Calendar.DayOfMonth = 1;"
Inserting missing rows with a join
Thank You
This will produce that output:
select distinct name, grade, Grade_Desc
from one
cross join two
If select is all you want then:
Select row_number() over(order by (select 1)) as id, * from
(Select distinct name from t1)t1
cross join t2
Here is fiddle http://sqlfiddle.com/#!6/a8a42/3
Try this out:
Create #Temp
DECLARE #Name VARCHAR(100) = 'Jim'
SELECT ROW_NUMBER() OVER (ORDER BY B.Grade DESC,B.CourseLevel DESC) ID,
A.Name,
B.Grade_Desc,
B.Grade,
A.YearWithUs,
B.[Course Level]
INTO #temp
FROM
(
SELECT DISTINCT Name,YearWithUs,Grade
FROM TableOne
WHERE Name = #Name
) A
INNER JOIN TableTwo B
ON A.Grade = B.Grade
Output One
SELECT *
FROM #temp
Output Two into #OutputTwo(temp table)
SELECT A.* INTO #OutputTwo
FROM #temp A
LEFT JOIN TableOne B
ON A.Grade = B.Grade
AND A.[Course Level] = B.[Course Level]
WHERE A.Grade IS NULL AND A.[Course Level] IS NULL
Added more information to clear up some confusions. Thanks.
I am trying to group sets of values in SQL. I have the following table and trying to somehow get the results as shown in the following table. I have explored group sets in SQL 2008, cubes, basic group by clauses, but I am not able to figure out the SQL query. Can someone please help. You can change the end resultant table format if you want but the basic idea is about how to count similar sets of values. In this table a,b,c exists 2 times so the count is 2 and x,y exists 3 times so the count is 3 and x, y, z exists 1 time so the count is 1. Please help.
UserId ProductId
1 a
1 b
1 c
2 x
2 y
3 x
3 y
4 x
4 y
5 a
5 b
5 c
6 x
6 y
6 z
ProductId Count
a 2
b 2
c 2
x 3
y 3
x 1
y 1
z 1
SELECT COUNT(`ProductId`),`ProductId ` WHERE 1 GROUP BY `ProductId` ORDER BY `ProductId` ASC
SELECT ProductId, COUNT(UserId) AS NbrOfUsers
FROM TABLE_NAME
GROUP BY ProductId, COUNT(UserId)
You're selecting ProductId & the count of how many UserId exist for that ProductId.
GROUP BY ProductId will group your counted UserId based on ProductId and also display the count as NbrOfUsers.
Your output will look like this:
ProductId NbrOfUsers
a 2
b 2
c 2
x 3
y 3
I have a data set with four columns (author, document, rating 1, rating 2)
How do I pick authors who have written a document that has been rated higher in rating 1 than rating 2, and has also written another document that has been rated higher in rating 2 than rating 1.
Basically:
AUTHOR DOCUMENT RATING 1 RATING 2
A 1 1 2
B 2 1 2
B 3 3 1
C 4 2 2
C 5 3 4
C 6 1 3
D 7 1 2
D 8 1 2
So my desired query will give me B and C because it has written docs that have had both higher and lower numbers in both ratings.
What I have:
SELECT DISTINCT author
FROM(
(SELECT author
FROM table_name
WHERE rating1 < rating2)
UNION
(SELECT author
FROM table_name
WHERE rating1 > rating2)
)
AS a
What I cant figure out is how to group the authors, test whether rating 1 and rating 2 are both higher and lower, output the name and then move on to the next group of authors. What the above prints is just the set of distinct names with either higher or lower numbers. So this one would print D as well for example.
What is my SQL code missing that would satisfy the criteria mentioned above
Try this,
select *
from myTable as t1
inner join MyTable as t2
on t1.author = t2.author
and t2.rating1 > t2.rating2
where t1.rating1 > t1.rating2