I have a table for absentees, and that table am storing the studentids of those who have been absent.
From this table I had to find total presentees and total absentees, for this I just joined the Sections table which contains the maximum capacity of particular Section.
For this my query was
select COUNT(Attendance.studentid) as Absentees
,Sections.Max-count(studentid) as Presentees
from Attendance
inner join Students
on students.StudentId=Attendance.StudentId
inner join Sections
on Sections.CourseId=students.CourseId
group by Sections.Max
Its working fine, the same way how can I find the gender wise presentees/absentees......gender column is in Students table, can anyone give me some idea, thanks in advance
Just add the gender column to your select ... columns and the group by, you'll end up with one row for each gender:
select COUNT(Attendance.studentid) as Absentees,
Sections.Max-count(studentid) as Presentees,
Students.Gender as Gender
from Attendance
inner join Students
on Students.StudentId=Attendance.StudentId
inner join Sections
on Sections.CourseId=Students.CourseId
group by Sections.Max, Students.Gender
Related
This one has only one table with three columns student, lect and score. for each lecture I need to find the students who have not got any score.
I have written the below query which uses outer joins, but it can do so only for one lect at a time.
Eg: see below I passed 'L02'
How do I get this working for all the lect values as in (L01,L02,L03...etc)
select distinct * from
(
select distinct Student from import1
where lect ='L02'
)i1
right outer join
(select distinct Student from import1) i2
on i1.Student=i2.Student
where i1.Student is null
output of above is
This works for L02. But, how do I modify above to include for all lect values without hardcoding the values of lect?
Sample data from table:
Need a dataset of all possible student/lecture pairs. If the one table contains all the students and lectures that need to be considered, this dataset can be built with:
SELECT Student, Lect FROM (SELECT DISTINCT Student FROM import1) AS S, (SELECT DISTINCT Lect FROM import1) AS L
Otherwise, need a table of all students and a table of all lectures then query:
SELECT Student, Lect FROM Students, Lectures
Now join that query to the scores table with compound link on both identifier fields and use appropriate filter criteria.
SELECT Query1.Student, Query1.Lect, import1.Score
FROM Query1 LEFT JOIN import1
ON (Query1.Lect = import1.Lect) AND (Query1.Student = import1.Student)
WHERE Score Is Null;
Tested with an Access database.
I need to know how many employees does each company have for each country they are present in? I have to join two tables (companies and cities) and sum number of employees for each country.
SELECT *, SUM(EMPLOYEES)
FROM COMPANIES WHERE
JOIN CITIES
ON COMPANIES.CITYNAME = CITIES.CITYNAME
doesn´t work...
Tables to join and sum employees for each country
A couple of tips,
Try to alias your joins so your not typing the full table names in your join statements
Add a group by on every field your not aggregating on for your sum to work
SELECT CI.COUNTRYNAME,CO.CITYNAME,CO.COMPANYNAME,CI.POPULATION,CI.COUNTRYNAME,
SUM(EMPLOYEES) AS TOTAL_EMPLOYEES
FROM COMPANIES AS CO
JOIN CITIES AS CI
ON CO.CITYNAME = CI.CITYNAME
GROUP BY CI.COUNTRYNAME,CO.COMPANYNAME,CO.CITYNAME,CI.POPULATION
https://rextester.com/DLZNT87647
I have this task:
Count the number of employees for every country. Show only those countries, when works more than 20 employees
employee_id is dedicated for Employees table
country belongs to different table - Countries table and we need country_name from this table
I have no idea how to solve this task. Below what I was able to create. I think we should use Inner Join.
SELECT a.employee_id
, b.country_name
, COUNT(a.employee_id) AS count
FROM employees a
INNER JOIN countries b ON a.employee_id = b.country_name
GROUP BY b.country_name
WHERE employee_id >20;
I think I need help from the beginning.
Thanks
Your join doesn't seem correct but as I don't know the table structure, I can't say what the right column is (I'm going to assume that it should be country_name. Even so, try this:
SELECT b.country_name
, COUNT(a.employee_id) AS count
FROM employees a
INNER JOIN countries b ON a.country_name = b.country_name
GROUP BY b.country_name
HAVING COUNT(employee_id) >20;
When grouping you need to use the HAVING statement to filter.
the result is very different when i separated statements...
SELECT Company.CompanyID,
Count(Projects2.CompanyID) as TotalProjects,
Count(Jobs2.CompanyID) as TotalJobs,
Count(Employees.CompanyID) as TotalEmployess
FROM Company JOIN
Projects2 ON Company.CompanyID = Projects2.CompanyID
JOIN Company Employees ON Company.CompanyID = Employees.CompanyID
JOIN Company Jobs2 ON Jobs2.CompanyID = Company.CompanyID
Group by Company.CompanyID
the result
why repeat the values?
any ideas?
I think you are counting the wrong ID. What is the primary key for the projects2, jobs2 and employees tables? Your query should be like this:
SELECT Company.CompanyID,
COUNT(DISTINCT Projects2.Primary_Key) as TotalProjects,
COUNT(DISTINCT Jobs2.Primary_Key) as TotalJobs,
COUNT(DISTINCT Employees.Primary_Key) as TotalEmployees
FROM Company
LEFT JOIN Projects2 ON Company.CompanyID = Projects2.CompanyID
LEFT JOIN Employees ON Company.CompanyID = Employees.CompanyID
LEFT JOIN Jobs2 ON Company.CompanyID = Jobs2.CompanyID
GROUP BY Company.CompanyID
Also, use LEFT joins instead of just JOIN and you don't need to keep repeating Company.
The reason you are getting the same count for each table is because of your joins. Say there are five records in the projects table with a given company ID but there are only three records in the jobs table with that ID. When you join company table to the project table you will have five records. Then when you join the jobs table, your joined table will have 15 (5*3) records for that company ID, because each job record will join to each of the five project records. Hence, you only want to select the distinct records from each table, using their primary key.
Your query is joining to the Company table 3 times (aliasing it as Employees and Jobs2 in the later instances). Just a typo?
You're getting the same values in each of the columns "TotalProjects", "TotalJobs", and "TotalEmployees", because your JOIN (in the future consider using INNER JOIN instead, as it does the same thing but is clearer) is producing results in which there are matching values across the joined tables - so you will end up with a like number of each result.
SQL Fiddle
I'm trying to force through zero values for grades that don't exist in my Results table, but do exist in my list of possible Grades table.
I've managed to join tables successfully in order to almost achieve this using this previous post as guidance up to a point.
As you can see from my fiddle the resultset is displaying NULL values for my Year and Subject columns and I would like these to display the relevant subject.
Don't use * in SELECT instead use specify the colums you need and use ISNULL and make it as zero like:
SELECT ISNULL(t.amount,0)
FROM [yourtable] y
left join [someOtherTable] t
ON y.id=t.id
What you need is a table of Subjects and Years, then cross join for grades...
create table Subjects(SubjectID INT, Subject Varchar(50));
create table YearSub (SubjectID INT, Year INT, CrateDate Date); -- Map your available subjects for each year in here
Once you have thiese, make a CTE to hold the full list of available subjects, years and grades
with AllGrades as
(select SubjectID, Year, Grade
from YearSub YS
cross join Grades
)
select ...
from AllGrades
left join ...
And so on
i think this is what you wanted.
first you get all combinition of student & grades by using CROSS JOIN
then you LEFT JOIN to the resutl table to the get the count
select s.year, subject grade, grade, count(wag) as Total
from student s
cross join grades g
left join results r on s.upn = r.upn and s.upn = r.upn
group by s.year, g.grade