I am having a problem with my SQL query using the count function.
When I don't have an inner join, it counts 55 rows. When I add the inner join into my query, it adds a lot to it. It suddenly became 102 rows.
Here is my SQL Query:
SELECT COUNT([fmsStage].[dbo].[File].[FILENUMBER])
FROM [fmsStage].[dbo].[File]
INNER JOIN [fmsStage].[dbo].[Container]
ON [fmsStage].[dbo].[File].[FILENUMBER] = [fmsStage].[dbo].[Container].[FILENUMBER]
WHERE [fmsStage].[dbo].[File].[RELATIONCODE] = 'SHIP02'
AND [fmsStage].[dbo].[Container].DELIVERYDATE BETWEEN '2016-10-06' AND '2016-10-08'
GROUP BY [fmsStage].[dbo].[File].[FILENUMBER]
Also, I have to do TOP 1 at the SELECT statement because it returns 51 rows with random numbers inside of them. (They are probably not random, but I can't figure out what they are.)
What do I have to do to make it just count the rows from [fmsStage].[dbo].[file].[FILENUMBER]?
First, your query would be much clearer like this:
SELECT COUNT(f.[FILENUMBER])
FROM [fmsStage].[dbo].[File] f INNER JOIN
[fmsStage].[dbo].[Container] c
ON v.[FILENUMBER] = c.[FILENUMBER]
WHERE f.[RELATIONCODE] = 'SHIP02' AND
c.DELIVERYDATE BETWEEN '2016-10-06' AND '2016-10-08';
No GROUP BY is necessary. Otherwise you'll just one row per file number, which doesn't seem as useful as the overall count.
Note: You might want COUNT(DISTINCT f.[FILENUMBER]). Your question doesn't provide enough information to make a judgement.
Just remove GROUP BY Clause
SELECT COUNT([fmsStage].[dbo].[File].[FILENUMBER])
FROM [fmsStage].[dbo].[File]
INNER JOIN [fmsStage].[dbo].[Container]
ON [fmsStage].[dbo].[File].[FILENUMBER] = [fmsStage].[dbo].[Container].[FILENUMBER]
WHERE [fmsStage].[dbo].[File].[RELATIONCODE] = 'SHIP02'
AND [fmsStage].[dbo].[Container].DELIVERYDATE BETWEEN '2016-10-06' AND '2016-10-08'
Related
I made a query and wanted to not have any duplicates but i got some times 3 duplicates and when i used DISTINCT or DISTINCTROW i got only 2 duplicates.
SELECT f.flight_code,
f.status,
a.airport_name,
a1.airport_name,
f.departing_date+f.departing_time AS SupposedDepartingTime,
f.landing_date+f.landing_time AS SupposedLandingTime,
de.actual_takeoff_date+de.actual_takeoff_time AS ActualDepartingTime,
SupposedLandingTime+(ActualDepartingTime-SupposedDepartingTime) AS ActualLandingTime
FROM
(((Flights AS f
LEFT JOIN Aireports AS a
ON a.airport_code = f.depart_ap)
LEFT JOIN Aireports AS a1
ON f.target_ap = a1.airport_code)
LEFT JOIN Irregular_Events AS ie
ON f.flight_code = ie.flight_code)
LEFT JOIN Delay_Event AS de
ON ie.IE_code = de.delay_code;
had to use LEFT JOIN because when i used INNER JOIN i missed some of the things i wanted to show because i wanted to see all the flights and not only the flights that got delayed or canceled.
This is the results when i used INNER JOIN, you can see only the flights that have the status "ביטול" or "עיכוב" and that is not what i wanted.
[the results with LEFT JOIN][2]
[2]: https://i.stack.imgur.com/cgE2G.png
and when i used DISTINCT where you see the rows with the NUMBER 6 on the first column it appear only two times
IMPORTANT!
I just checked my query and all the tables i use there and i saw my problem but dont know how to fix it!
in the table Irregular_Events i have more the one event for flights 3,6 and 8 and that is why when i use LEFT JOIN i see more even thou i use distinct, please give me some help!
Not entirely sure without seeing the table structure, but this might work:
SELECT f.flight_code,
f.status,
a.airport_name,
a1.airport_name,
f.departing_date+f.departing_time AS SupposedDepartingTime,
f.landing_date+f.landing_time AS SupposedLandingTime,
de.actual_takeoff_date+de.actual_takeoff_time AS ActualDepartingTime,
SupposedLandingTime+(ActualDepartingTime-SupposedDepartingTime) AS ActualLandingTime
FROM
((Flights AS f
LEFT JOIN Aireports AS a
ON a.airport_code = f.depart_ap)
LEFT JOIN Aireports AS a1
ON f.target_ap = a1.airport_code)
LEFT JOIN
(
SELECT
ie.flight_code,
de1.actual_takeoff_date,
de1.actual_takeoff_time
FROM
Irregular_Events ie
INNER JOIN Event AS de1
ON ie.IE_code = de1.delay_code
) AS de
ON f.flight_code = de.flight_code
It is hard to tell what is the problem with your query without any sample of the output, and without any description of the structure of your tables.
But your problem is that your are querying from the flights table, which [I assume] can be linked to multiple irregular_events, which can possibly also be linked to multiple delay_event.
If you want to get only one row per flight, you need to make sure your joins return only one row too. Maybe you can do it by adding one more condition to the join, or by adding a condition in a sub-query.
EDIT
You could try to add a GROUP BY to the query:
GROUP BY
f.flight_code,
f.status,
a.airport_name,
a1.airport_name;
I am getting different results for the following two queries and I have no idea why. The only difference is one has an IN and one has an equals.
Before I go into the queries you should know that I found a better way to do it by moving the subquery into a common table expression, but this is still driving me crazy! I really want to know what caused the issue in the first place, I am asking out of curiosity
Here's the first query:
use [DB.90_39733]
Select distinct x.uniqproducer, cn.Firstname,cn.lastname,e.code,
ecn.FirstName, ecn.LastName, ecn.entid, x.uniqline
from product x
join employ e on e.EmpID=x.uniqproducer
join contactname cn on cn.uniqentity=e.uniqentity
join [ETL_GAWR92]..idlookupentity ide on ide.enttype='EM'
and ide.UniqEntity=e.UniqEntity
left join [ETL_GAWR92]..EntConName ecn on ecn.entid=ide.empid
and ecn.opt='Y'
Where x.UniqProducer =(SELECT TOP 1 idl.UniqEntity
FROM [ETL_GAWR92]..IDLookupEntity idl
LEFT JOIN [ETL_GAWR92]..Employ e2 ON e2.ProdID = ''
WHERE idl.empID = e2.EmpID AND
idl.EntType = 'EM')
And the second one:
use [DB.90_39733]
Select distinct x.uniqproducer, cn.Firstname,cn.lastname,e.code,
ecn.FirstName, ecn.LastName, ecn.entid, x.uniqline
from product x
join employ e on e.EmpID=x.uniqproducer
join contactname cn on cn.uniqentity=e.uniqentity
join [ETL_GAWR92]..idlookupentity ide on ide.enttype='EM'
and ide.UniqEntity=e.UniqEntity
left join [ETL_GAWR92]..EntConName ecn on ecn.entid=ide.empid
and ecn.opt='Y'
Where x.UniqProducer IN (SELECT TOP 1 idl.UniqEntity
FROM [ETL_GAWR92]..IDLookupEntity idl
LEFT JOIN [ETL_GAWR92]..Employ e2 ON e2.ProdID = ''
WHERE idl.empID = e2.EmpID AND
idl.EntType = 'EM')
The first query returns 0 rows while the second query returns 2 rows.The only difference is x.UniqProducer = versus x.UniqProducer IN for the last where clause.
Thanks for your time
SELECT TOP 1 doesn't guarantee that the same record will be returned each time.
Add an ORDER BY to your select to make sure the same record is returned.
(SELECT TOP 1 idl.UniqEntity
FROM [ETL_GAWR92]..IDLookupEntity idl
LEFT JOIN [ETL_GAWR92]..Employ e2 ON e2.ProdID = ''
WHERE idl.empID = e2.EmpID AND
idl.EntType = 'EM' ORDER BY idl.UniqEntity)
I would guess (with strong emphasis on the word “guess”) that the reason is based on how equals and in are processed by the query engine. For equals, SQL knows it needs to do a comparison with a specific value, where for in, SQL knows it needs to build a subset, and find if the "outer" value is in that "inner" subset. Yes, the end results should be the same as there’s only 1 row returned by the subquery, but as #RickS pointed out, without any ordering there’s no guarantee of which value ends up “on top” – and the (sub)query plan used to build the in - driven subquery might differ from that used by the equals pull.
A follow-up question: which is the correct dataset? When you analyze the actual data, should you have gotten zero, two, or a different number of rows?
My title is probably not very clear, so I made a little schema to explain what I'm trying to achieve. The xxxx_uid labels are foreign keys linking two tables.
Goal: Retrieve a column from the grids table by giving a proj_uid value.
I'm not very good with SQL joins and I don't know how to build a single query that will achieve that.
Actually, I'm doing 3 queries to perform the operation:
1) This gives me a res_uid to work with:
select res_uid from results where results.proj_uid = VALUE order by res_uid asc limit 1"
2) This gives me a rec_uid to work with:
select rec_uid from receptor_results
inner join results on results.res_uid = receptor_results.res_uid
where receptor_results.res_uid = res_uid_VALUE order by rec_uid asc limit 1
3) Get the grid column I want from the grids table:
select grid_name from grids
inner join receptors on receptors.grid_uid = grids.grid_uid
where receptors.rec_uid = rec_uid_VALUE;
Is it possible to perform a single SQL that will give me the same results the 3 I'm actually doing ?
You're not limited to one JOIN in a query:
select grids.grid_name
from grids
inner join receptors
on receptors.grid_uid = grids.grid_uid
inner join receptor_results
on receptor_results.rec_uid = receptors.rec_uid
inner join results
on results.res_uid = receptor_results.res_uid
where results.proj_uid = VALUE;
select g.grid_name
from results r
join resceptor_results rr on r.res_uid = rr.res_uid
join receptors rec on rec.rec_uid = rr.rec_uid
join grids g on g.grid_uid = rec.grid_uid
where r.proj_uid = VALUE
a small note about names, typically in sql the table is named for a single item not the group. thus "result" not "results" and "receptor" not "receptors" etc. As you work with sql this will make sense and names like you have will seem strange. Also, one less character to type!
So I got this query:
Data structure:
Users
id---inlog----name----more stuff
llntoets
id---code----inlog----more stuff
oefeningen
id---speler---status----morestuff
(inlog and speler are always the same values for a user)
SELECT
// Some other stuff working
SUM(o.status) AS oefn
FROM users AS u
LEFT JOIN llntoets AS l
ON (u.inlog = l.inlog)
LEFT JOIN oefeningen AS o
ON (u.inlog = o.speler) AND o.status = 'afgewerkt'
WHERE
code = '$code'
GROUP BY l.inlog
ORDER BY klas ASC, klasnr ASC
Everything runs fine except 1 thing the oefn variable. It shows a number sometimes it shows the correct value and sometimes it shows a value that is much higher than it should be. Someone told me it could be because of the GROUP BY. Can someone help me pls?
It is supposed to count the total records from table oefeningen where status = 'afgewerkt' and where the speler is the inlog from users. Thanks, if you got other questions ask will try to explain more.
the SUM(o.status) in your query it is not supposed to count the total records of table oefeningen.
that sum is the sum of the values of all the joined rows that satisfy your criteria that can be a much higher number.
also note that applying the filter o.status = 'afgewerkt' you are performing a JOIN even if you wrote LEFT JOIN throghout the query.
I'm trying to using the aggregation features of the django ORM to run a query on a MSSQL 2008R2 database, but I keep getting a timeout error. The query (generated by django) which fails is below. I've tried running it directs the SQL management studio and it works, but takes 3.5 min
It does look it's aggregating over a bunch of fields which it doesn't need to, but I wouldn't have though that should really cause it to take that long. The database isn't that big either, auth_user has 9 records, ticket_ticket has 1210, and ticket_watchers has 1876. Is there something I'm missing?
SELECT
[auth_user].[id],
[auth_user].[password],
[auth_user].[last_login],
[auth_user].[is_superuser],
[auth_user].[username],
[auth_user].[first_name],
[auth_user].[last_name],
[auth_user].[email],
[auth_user].[is_staff],
[auth_user].[is_active],
[auth_user].[date_joined],
COUNT([tickets_ticket].[id]) AS [tickets_captured__count],
COUNT(T3.[id]) AS [assigned_tickets__count],
COUNT([tickets_ticket_watchers].[ticket_id]) AS [tickets_watched__count]
FROM
[auth_user]
LEFT OUTER JOIN [tickets_ticket] ON ([auth_user].[id] = [tickets_ticket].[capturer_id])
LEFT OUTER JOIN [tickets_ticket] T3 ON ([auth_user].[id] = T3.[responsible_id])
LEFT OUTER JOIN [tickets_ticket_watchers] ON ([auth_user].[id] = [tickets_ticket_watchers].[user_id])
GROUP BY
[auth_user].[id],
[auth_user].[password],
[auth_user].[last_login],
[auth_user].[is_superuser],
[auth_user].[username],
[auth_user].[first_name],
[auth_user].[last_name],
[auth_user].[email],
[auth_user].[is_staff],
[auth_user].[is_active],
[auth_user].[date_joined]
HAVING
(COUNT([tickets_ticket].[id]) > 0 OR COUNT(T3.[id]) > 0 )
EDIT:
Here are the relevant indexes (excluding those not used in the query):
auth_user.id (PK)
auth_user.username (Unique)
tickets_ticket.id (PK)
tickets_ticket.capturer_id
tickets_ticket.responsible_id
tickets_ticket_watchers.id (PK)
tickets_ticket_watchers.user_id
tickets_ticket_watchers.ticket_id
EDIT 2:
After a bit of experimentation, I've found that the following query is the smallest that results in the slow execution:
SELECT
COUNT([tickets_ticket].[id]) AS [tickets_captured__count],
COUNT(T3.[id]) AS [assigned_tickets__count],
COUNT([tickets_ticket_watchers].[ticket_id]) AS [tickets_watched__count]
FROM
[auth_user]
LEFT OUTER JOIN [tickets_ticket] ON ([auth_user].[id] = [tickets_ticket].[capturer_id])
LEFT OUTER JOIN [tickets_ticket] T3 ON ([auth_user].[id] = T3.[responsible_id])
LEFT OUTER JOIN [tickets_ticket_watchers] ON ([auth_user].[id] = [tickets_ticket_watchers].[user_id])
GROUP BY
[auth_user].[id]
The weird thing is that if I comment out any two lines in the above, it runs in less that 1s, but it doesn't seem to matter which lines I remove (although obviously I can't remove a join without also removing the relevant SELECT line).
EDIT 3:
The python code which generated this is:
User.objects.annotate(
Count('tickets_captured'),
Count('assigned_tickets'),
Count('tickets_watched')
)
A look at the execution plan shows that SQL Server is first doing a cross-join on all the table, resulting in about 280 million rows, and 6Gb of data. I assume that this is where the problem lies, but why is it happening?
SQL Server is doing exactly what it was asked to do. Unfortunately, Django is not generating the right query for what you want. It looks like you need to count distinct, instead of just count: Django annotate() multiple times causes wrong answers
As for why the query works that way: The query says to join the four tables together. So say an author has 2 captured tickets, 3 assigned tickets, and 4 watched tickets, the join will return 2*3*4 tickets, one for each combination of tickets. The distinct part will remove all the duplicates.
what about this?
SELECT auth_user.*,
C1.tickets_captured__count
C2.assigned_tickets__count
C3.tickets_watched__count
FROM
auth_user
LEFT JOIN
( SELECT capturer_id, COUNT(*) AS tickets_captured__count
FROM tickets_ticket GROUP BY capturer_id ) AS C1 ON auth_user.id = C1.capturer_id
LEFT JOIN
( SELECT responsible_id, COUNT(*) AS assigned_tickets__count
FROM tickets_ticket GROUP BY responsible_id ) AS C2 ON auth_user.id = C2.responsible_id
LEFT JOIN
( SELECT user_id, COUNT(*) AS tickets_watched__count
FROM tickets_ticket_watchers GROUP BY user_id ) AS C3 ON auth_user.id = C3.user_id
WHERE C1.tickets_captured__count > 0 OR C2.assigned_tickets__count > 0
--WHERE C1.tickets_captured__count is not null OR C2.assigned_tickets__count is not null -- also works (I think with beter performance)