Let's say I had a table of machines our employees use called machineManufacturer, which had the columns ID, and manufacturer. Then, I had another table that was added to whenever that machine was used called deviceUsage, which has the columns ID, and date.
I want to know the number of times used grouped according to manufacturer.
I believe the answer has something to do with COUNT and an INNER JOIN, but I am fairly new to SQL (only took one databases class in school).
I have tried something like:
SELECT manufacturer
FROM machineManufacturer
INNER JOIN deviceUsage
ON machineManufacturer.ID = deviceUsage.ID
which returns a big column of manufacturers, without any count. I am trying to count them and get a table like--
Manufacturer: Count
Dell: 30
HP: 27
Mac: 9
Lenovo: 14
etc.
Any comments welcome. Thank you for your time.
I think you want group by:
SELECT MF.manufacturer, count(*)
FROM machineManufacturer MF INNER JOIN
deviceUsage D
ON MF.ID = D.ID
GROUP BY MF.manufacturer;
Related
I have 2 tables. One lists all the goals scored in the English Premier League and who scored it and the other, the squad numbers of each player in the league.
I want to do a join so that the table sums the total number of goals by player name, and then looks up the squad number of that player.
Table A [goal_scorer]
[]1
Table B [squads]
[]2
I have the SQL query below:
SELECT goal_scorer.*,sum(goal_scorer.number),squads.squad_number
FROM goal_scorer
Inner join squads on goal_scorer.name=squads.player
group by goal_scorer.name
The issue I have is that in the result, the sum of 'number' is too high and seems to include duplicate rows. For example, Aaron Lennon has scored 33 times, not 264 as shown below.
Maybe you want something like this?
SELECT goal_scorer.*, s.total, squads.squad_number
FROM goal_scorer
LEFT JOIN (
SELECT name, sum(number) as total
FROM goal_scorer
GROUP BY name
) s on s.name = goal_scorer.name
JOIN squads on goal_scorer.name=squads.player
There are other ways to do it, but here I'm using a sub-query to get the total by player. NB: Most modern SQL platforms support windowing functions to do this too.
Also, probably don't need the left on the sub-query (since we know there will always be at least one name), but I put it in case your actual use case is more complicated.
Can you try this if you are using sql-server?
select *
from squads
outer apply(
selecr sum(goal_scorer.number) as score
from goal_scorer where goal_scorer.name=squads.player
)x
I am trying to count all the values in one column and then multiply this number by a value in a different table. So far I have:
SELECT CLUB_FEE * COUNT(MEMBER_ID) AS VALUE
FROM CLUB, SUBSCRIPTION
WHERE CLUB_ID = 'CLUB1';
This is not working however, can anyone please help?
I also need help doing this for multiple clubs. Is it possible to do it all in one statement for all clubs and then get the average?
Presumably, you intend something like this:
SELECT MAX(c.CLUB_FEE) * COUNT(MEMBER_ID) AS VALUE
FROM CLUB c JOIN
SUBSCRIPTION s
ON c.CLUB_ID = s.CLUB_ID
WHERE c.CLUB_ID = 'CLUB1';
You can also write this as:
SELECT SUM(c.CLUB_FEE) AS VALUE
FROM CLUB c JOIN
SUBSCRIPTION s
ON c.CLUB_ID = s.CLUB_ID
WHERE c.CLUB_ID = 'CLUB1';
I thought the first version would be clearer, because the OP specifies COUNT() in the question.
If you want it for all clubs that have subscribers:
SELECT SUM(c.CLUB_FEE) AS VALUE
FROM CLUB c JOIN
SUBSCRIPTION s
ON c.CLUB_ID = s.CLUB_ID
GROUP BY c.CLUB_ID;
From inspecting the explain plans, it seems the following version may be a bit more efficient (since it avoids a join and uses only one aggregation). If you need this for ALL clubs at the same time, then probably all solutions will have the same "optimizer cost" (they will all do a join at some point).
select club_fee * (select count(member_id) from subscription where club_id = 'CLUB1')
from club
where club_id = 'CLUB1'
So now the only aggregate function is pushed into a subquery and the rest does not need either a join or another aggregate function.
Of course, this only matters if performance is important; it may very well not be.
I create a new view in SQL Server 2008 from two tables that have relation on a field. I want to create a report and do grouping on that common field.
For example:
table1: student(ID,first-name,last-name,phone,address,...)
table2: courses(ID,fk_ID,Course,....)
Now I want to have report that shows all data from both tables with grouping on ID from student table, that must show courses information separated for every student.
my query is:
SELECT TOP (100) PERCENT
dbo.tbl_student.ID,
dbo.tbl_student.firstname, dbo.tbl_student.lastname,
dbo.tbl_courses.Coursename,
dbo.tbl_Courses.CourseDate, dbo.tbl_courses.coursetype,
FROM
dbo.tbl_student LEFT OUTER JOIN
dbo.tbl_courses ON dbo.tbl_student.ID = dbo.tbl_courses.fk_id
ORDER BY
dbo.tbl_student.firstname DESC
But when I create a new report from this view, it shows just one record for every group. I spent 2 hours to solve the problem but I did not succeed.
please help me to create report from two or more tables.
Now it shows one record duplicates for several times for every group
Have you tried a query like this:
SELECT s.[ID], s.[first-name], s.[last-name], s.[phone], ...
c.[ID], c.[Course], ...
FROM student s
LEFT OUTER JOIN
courses c ON s.[ID] = c.[fk_ID]
I have three tables like
I want to display the leave types with the count. For that I have written a query like
SELECT VM.vacation_id,
VM.vacation_desc,
isnull(sum(VR.total_hours_applied),0) AS totalCount
FROM EMPTYPE_VACATIONCONFIG VC
LEFT JOIN HR_Vacation_Master VM ON VC.VACATIONID=VM.vacation_id
INNER JOIN HR_Employee_Vacation_Request VR ON VR.vacation_id=VM.vacation_id
WHERE VR.employee_id=156
AND VC.BRANCHID=20
GROUP BY VM.vacation_desc,
VM.vacation_id
my query is working fine and giving results of existed vacationids only. like
I want third leave alos with zero total.
If the employee not applied any leave(in second table), that record not coming in list. I want that record also with the totalCount zero.
How can I do it
This is because of VR.employee_id=156 you are not allowing null row.
You can do that :
SELECT VM.vacation_id,
VM.vacation_desc,
isnull(sum(VR.total_hours_applied),0) AS totalCount
FROM EMPTYPE_VACATIONCONFIG VC
LEFT JOIN HR_Vacation_Master VM ON VC.VACATIONID=VM.vacation_id
LEFT JOIN HR_Employee_Vacation_Request VR
ON VR.vacation_id=VM.vacation_id AND VR.employee_id=156
WHERE VC.BRANCHID=20
GROUP BY VM.vacation_desc,
VM.vacation_id
Leave me a comment if this not works, I have some other ideas.
If one employee didn't apply any leave, there shouldn't have a record with his(or her) employee id in table HR_Employee_Vacation_Request , right? So I think you should use HR_Vacation_Master left outer join table HR_Employee_Vacation_Request .
I have a table B with cids and cities. I also have a table C that has these cids with extra information. I want to list all the cids in table C that are associated with ALL appearances of a given city in Table B.
My current solution relies on counting the number of times the given city appears in Table B and selecting only the cids that appear that many times. I don't know all the SQL syntax yet, but is there a way to select for this kind of pattern?
My current solution:
SELECT Agents.aid
FROM Agents, Customers, Orders
WHERE (Customers.city='Duluth')
AND (Agents.aid = Orders.aid)
AND (Customers.cid = Orders.cid)
GROUP BY Agents.aid
HAVING count(Agents.aid) > 1
It only works because I know right now with the HAVING statement.
Thanks for the help. I wasn't sure how to google this problem, since it's pretty specific.
EDIT: I'm pinpointing my problem a bit. I need to know how to determine if EVERY row in a table has a certain value for a field. Declaring a variable and counting the rows in a sub-selection and filtering out my results by IDs that appear that many times works, but It's really ugly.
There HAS to be a way to do this without explicitly count()ing rows. I hope.
Not an answer to your question, but a general improvement.
I'd recommend using JOIN syntax to join your tables together.
This would change your query to be:
SELECT Agents.aid
FROM Agents
INNER JOIN Orders
ON Agents.aid = Orders.aid
INNER JOIN Customers
ON Customers.cid = Orders.cid
WHERE Customers.city='Duluth'
GROUP BY Agents.aid
HAVING count(Agents.aid) > 1
What variant of SQL are you using?
To start with, you can (and should) use JOIN instead of doing it in the WHERE clause, e.g.,
select Agents.aid
from Agents
join Orders on Agents.aid = Orders.aid
join Customers on Customers.cid = Orders.cid
where Customers.city = 'Duluth'
group by Agents.aid
having count(Agents.aid) > 1
After that, I'm afraid I might be a little lost. Using the table names in your example query, what (in English, not pseudocode) are you trying to retrieve? For example, I think your sample query is retrieving the PK for all Agents that have been involved in at least 2 Orders involving Customers in Duluth.
Also, some table definitions for Agents, Orders, and Customers might help (then again, they might be irrelevant).
I'm not sure if I understood you problem, but I think the following query is what you want:
SELECT *
FROM customers b
INNER JOIN orders c USING (cid)
WHERE b.city = 'Duluth'
AND NOT EXISTS (SELECT 1
FROM customers b2
WHERE b2.city = b.city
AND b2.cid <> cid);
Probably you will need some indexes on these columns.