SELECT organizations_organization.code as organization,
core_user.email as Created_By,
assinees.email as Assigned_To,
from tickets_ticket
JOIN organizations_organization on tickets_ticket.organization_id = organizations_organization.id
JOIN core_user on tickets_ticket.created_by_id = core_user.id
Left JOIN core_user as assinees on assinees.id = tickets_ticket.currently_assigned_to_id
In the above query, if tickets_ticket.currently_assigned_to_id is null then that that row from tickets_ticket is not returned
> Records In tickets_ticket = 109
> Returned Records = 4 (out of 109 4 row has value for currently_assigned_to_id rest 105 are null )
> Expected Records = 109 (with nulll set for Assigned_To)
Note I am trying to achieve multiple joins on the same table
LEFT JOIN can not kill output records,
your problem is here:
JOIN core_user on tickets_ticket.created_by_id = core_user.id
this join kills non-matching records
try
LEFT JOIN core_user on tickets_ticket.created_by_id = core_user.id
First, this is not the actual code you are running. There is a comma before the from clause that would cause a syntax error. If you have left out a where clause, then that would explain why you are seeing no rows.
When using left joins, conditions on the first table go in the where clause. Conditions on subsequent tables go in the on clause.
That said, a where clause may not be the problem. I would suggest using left joins from the first table onward -- along with table aliases:
select oo.code as organization, cu.email as Created_By, a.email as Assigned_To,
from tickets_ticket tt left join
organizations_organization oo
on tt.organization_id = oo.id left join
core_user cu
on tt.created_by_id = cu.id left join
core_user a
on a.id = tt.currently_assigned_to_id ;
I suspect that you have data in your data model that is unexpected -- perhaps bad organizations, perhaps bad created_by_id. Keep all the tickets to see what is missing.
That said, you should probably be including something like tt.id in the result set to identify the specific ticket.
Related
My application generates the following SQL-request to get the records matching teamkey:
select cr.callid, t.teamname, u.userfirstname
from callrecord cr
left join agentrecord ar on cr.callid = ar.callid
left join users u on ar.agentkey = u.userkey
left join teams t on u.teamkey = t.teamkey
where t.teamkey in (1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16)
This works fine.
When I tried to get the records NOT matching teamkey, the first idea was:
select cr.callid, t.teamname, u.userfirstname
from callrecord cr
left join agentrecord ar on cr.callid = ar.callid
left join users u on ar.agentkey = u.userkey
left join teams t on u.teamkey = t.teamkey
where t.teamkey not in (1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16)
This returns no data. Seems this requires completely different SQL request.
Please help to switch my mind in proper direction.
Record from callrecord table may have no matching record in agentrecord table, also record from users table may have no matching record in teams table, but I want them in the output.
Your query should work, for example a team key of 17 should be returned.
The condition is not exactly the negation of the original because in SQL null values never compare as true (look up SQL three-valued logic, they evaluate as unknown).
Only is null and is distinct from (standard but not supported by most RDBMS) can be used to compare nulls.
So the only rows you might be missing are those that don't have a team. If teamkey is null (in the table or because one of the join did not match), it would not be returned.
You can get those results back by changing your condition to t.teamkey not in (...) or t.teamkey is null
I have been using sql for a long time, but I am now working in Databricks and I am getting a very strange result. I have a table called block_durations with a set of ids (called block_ts), and I have another table called mergetable, which I want to left join to that table. Mergetable is indexed by acct_id and block_ts, so it has many different records for each block_ts. I want to keep the rows in block_durations that don't match, and if there are multiple matches in mergetable I want there to be multiple corresponding entries in the resulting join, as you would expect from a left join.
But this is not happening. In order to demonstrate this, I am showing the result of joining mergetable, after filtering for a single acct_id so that there is at most one match per block_ts.
select count(*) from mergetable where acct_id = '0xfbb1b73c4f0bda4f67dca266ce6ef42f520fbb98'
16579
select count(*) from block_durations
82817
select count(*) from
(
SELECT
mt.*,
bd.block_duration
FROM
block_durations bd
left outer JOIN mergetable mt
ON mt.block_ts = bd.block_ts
where acct_id='0xfbb1b73c4f0bda4f67dca266ce6ef42f520fbb98'
) countTable
16579
As you can see, even though there are >80000 records in block_durations, most of them are getting lost in the left join. Why is this happening? I thought the whole point of a left join is that the non-matching rows of the left table are kept. This is exactly the behavior I would expect from an inner join -- and indeed when I switch to an inner join nothing changes.
Could someone please help me figure out what's going on?
-Paul
All rows from left side of the join are preserved, but later on you run WHERE ... condition on that which removed rows not matching the condition.
Merge your WHERE condition into JOIN condition:
SELECT
mt.*,
bd.block_duration
FROM
block_durations bd
left outer JOIN mergetable mt
ON mt.block_ts = bd.block_ts AND acct_id='0xfbb1b73c4f0bda4f67dca266ce6ef42f520fbb98'
You can also filter mergetable before you run JOIN on the results:
SELECT
mt.*,
bd.block_duration
FROM
block_durations bd
left outer JOIN (SELECT * FROM mergetable WHERE acct_id='0xfbb1b73c4f0bda4f67dca266ce6ef42f520fbb98') mt
ON mt.block_ts = bd.block_ts
I have a query that gives me 759 rows:
Select
buildingID
,buildingAddress
,building_zip
From
BuildingTable
However, when I join the table to get a column from another table, the number of rows is reduced to 707
Select
buildingID
,buildingaddress
,building_zip
,b.surveyCost
From
BuildingTable as A
Inner Join SurveyTable as B
On a.buildingAddress = b.address
What is the best way to test which rows I lost and why? and how do I prevent this from happening? I was thinking that maybe some of the buildings don't have survey costs and therefore it was only showing me the ones that have costs, but I see some null values there so that was not the issue, I think.
If you need extra information let me know. Thanks
To find the rows you have lost, just replace the inner join with a left join and look for missing rows:
Select bt.*
From BuildingTable bt left join
SurveyTable st
on bt.buildingAddress = st.address
where st.address is null;
Note that rows can also be duplicated in both tables, so you might have more missing rows than you expect.
You can find the row which rows are lost usig a left join between original query and resulting query where the join is nulll
Select
buildingID
,buildingAddress
,building_zip
From
BuildingTable t1
left join (
Select
buildingID
,buildingaddress
,building_zip
,b.surveyCost
From
BuildingTable as A
Inner Join SurveyTable as B
On a.buildingAddress = b.address
) t2 on t1.buildingID = t2.buildingID
where t2.buildingID is null
but why .. depend on you knowledge of the data
Why, in this query, is the final 'WHERE' clause needed to limit duplicates?
The first LEFT JOIN is linking programs to entities on a UID
The first INNER JOIN is linking programs to a subquery that gets statistics for those programs, by linking on a UID
The subquery (that gets the StatsForDistributorClubs subset) is doing a grouping on UID columns
So, I would've thought that this would all be joining unique records anyway so we shouldn't get row duplicates
So why the need to limit based on the final WHERE by ensuring the 'program' is linked to the 'entity'?
(irrelevant parts of query omitted for clarity)
SELECT LmiEntity.[DisplayName]
,StatsForDistributorClubs.*
FROM [Program]
LEFT JOIN
LMIEntityProgram
ON LMIEntityProgram.ProgramUid = Program.ProgramUid
INNER JOIN
(
SELECT e.LmiEntityUid,
sp.ProgramUid,
SUM(attendeecount) [Total attendance],
FROM LMIEntity e,
Timetable t,
TimetableOccurrence [to],
ScheduledProgramOccurrence spo,
ScheduledProgram sp
WHERE
t.LicenseeUid = e.lmientityUid
AND [to].TimetableOccurrenceUid = spo.TimetableOccurrenceUid
AND sp.ScheduledProgramUid = spo.ScheduledProgramUid
GROUP BY e.lmientityUid, sp.ProgramUid
) AS StatsForDistributorClubs
ON Program.ProgramUid = StatsForDistributorClubs.ProgramUid
INNER JOIN LmiEntity
ON LmiEntity.LmiEntityUid = StatsForDistributorClubs.LmiEntityUid
LEFT OUTER JOIN Region
ON Region.RegionId = LMIEntity.RegionId
WHERE (
[Program].LicenseeUid = LmiEntity.LmiEntityUid
OR
[LMIEntityProgram].LMIEntityUid = LmiEntity.LmiEntityUid
)
If you were grouping in your outer query, the extra criteria probably wouldn't be needed, but only your inner query is grouped. Your LEFT JOIN to a grouped inner query can still result in multiple records being returned, for that matter any of your JOINs could be the culprit.
Without seeing sample of duplication it's hard to know where the duplicates originate from, but GROUPING on the outer query would definitely remove full duplicates, or revised JOIN criteria could take care of it.
You have in result set:
SELECT LmiEntity.[DisplayName]
,StatsForDistributorClubs.*
I suppose that you dublicates comes from LMIEntityProgram.
My conjecture: LMIEntityProgram - is a bridge table with both LmiEntityId an ProgramId, but you join only by ProgramId.
If you have several LmiEntityId for single ProgramId - you must have dublicates.
And this dublicates you're filtering in WHERE:
[LMIEntityProgram].LMIEntityUid = LmiEntity.LmiEntityUid
You can do it in JOIN:
LEFT JOIN LMIEntityProgram
ON LMIEntityProgram.ProgramUid = Program.ProgramUid
AND [LMIEntityProgram].LMIEntityUid = LmiEntity.LmiEntityUid
I'm trying to fetch some data from a database.
I want to select an employee, and if available, all appointments and other data related to that employee.
This is the query:
SELECT
TA.id,
TEI.displayname,
TA.threatment_id,
TTS.appointment_date,
TEI.displayname
FROM
tblemployee AS TE
LEFT OUTER Join tblappointment AS TA ON TE.employeeid = TA.employee_id
Inner Join tblthreatment AS T ON TA.threatment_id = T.threatmentid
Inner Join tblappointments AS TTS ON TTS.id = TA.appointments_id AND
TTS.appointment_date = '2009-09-28'
INNER Join tblemployeeinfo AS TEI ON TEI.employeeinfoid = TE.employeeinfoid
Inner Join tblcustomercard AS TCC ON TCC.customercardid = TTS.customercard_id
WHERE
TE.employeeid = 4
The problem is, it just returns null for all fields selected when there are no appointments. What am I not getting here?
Edit:
For clearity, i removed some of the collumns. I removed one too many. TEI.displayname should at least be displayed.
Looking at the list of columns returned by your query, you will notice that they all come from the "right" side of the LEFT OUTER JOIN. You do not include any columns from the "left" side of the join. Therefore, the expected result is the one you are observing — NULL values supplied for all right-hand columns in the result set for those rows that have no right-hand rows returned.
To see data even for those rows, include some columns from TE (tblemployee) in the result set.
Looking at your query I'm guessing that the situation is a bit more complex and that some of those tables on the right-hand side of the join should be moved to the left-hand side and, furthermore, that some of the other tables might possibly require their own OUTER joins to participate correctly in the query.
Edited w/ response to questioner's comment:
You have an odd situation (maybe not odd at all, depending on your application) in which you have an employee table and a separate employee information (employeeinfo) table.
Because you are joining the employeeinfo to the appointments table with an INNER join you can effectively think of them as a single table in terms of how they contribute to the final result set. Because this combined table REQUIRES a record in the appointments table and because this combined table is joined into the main result set with a LEFT OUTER join, the effect is that the employeeinfo record is not found if there's no appointment to link it to.
If you move the employeeinfo table to the left side of the join, or replace the employee table w/ the employeeinfo table, you should get the results you want.
In your query, you LEFT OUTER JOIN to the tblappointment table, but then you INNER JOIN to the tblthreatment and tblappointments tables.
You should try and structure your query in the order that you expect data to be there. Then in most simple queries, once you perform an OUTER join, most tables after that will be an OUTER join. This is by NO MEANS a rule and complex queries can vary, but in the marjority of simple queries its a good practice.
Try something like this for your query.
SELECT
TA.id,
TEI.displayname,
TA.threatment_id,
TTS.appointment_date
FROM
tblemployee AS TE
INNER Join
tblemployeeinfo AS TEI
ON
TEI.employeeinfoid = TE.employeeinfoid
LEFT OUTER Join
tblappointment AS TA
ON
TE.employeeid = TA.employee_id
LEFT OUTER JOIN
tblthreatment AS T
ON
TA.threatment_id = T.threatmentid
LEFT OUTER JOIN
tblappointments AS TTS
ON
TTS.id = TA.appointments_id
AND
TTS.appointment_date = '2009-09-28'
LEFT OUTER JOIN
tblcustomercard AS TCC
ON
TCC.customercardid = TTS.customercard_id
WHERE
TE.employeeid = 4
The issue is that the way you're joining (most of everything is joining to your left outer-joined table) whenever you're joining off of that, if the value in the outer joined table is nothing, there is nothing for the other fields to join to. Try to re-adjust your query so everything is joining off of your employeeID. I normally use left joined tables after I've limited everything down as much as possible with inner joins.
So my query would be something like:
SELECT
TA.id,
TEI.displayname,
TA.threatment_id,
TTS.appointment_date
FROM
tblemployee AS TE
INNER Join tblemployeeinfo AS TEI ON TEI.employeeinfoid = TE.employeeinfoid
Inner Join tblthreatment AS T ON TA.threatment_id = T.threatmentid
Inner Join tblappointments AS TTS ON TTS.id = TA.appointments_id AND
TTS.appointment_date = '2009-09-28'
Inner Join tblcustomercard AS TCC ON TCC.customercardid = TTS.customercard_id
LEFT OUTER Join tblappointment AS TA ON TE.employeeid = TA.employee_id
WHERE
TE.employeeid = 4
where the last outer join just gives me one column worth of information, not using it all to join more things onto. For speed, you also want to try to limit your information down as fast as possible with your first few inner joins, and then you do the outer joins last to join possible null values on to the smallest dataset you can. I hope this helps, if it's confusing, I'm sorry... I haven't had my caffeine yet.
The query is performing as it should.
A left out join will select all records from one table, join them with the records in another, and produce nulls where no records in the second table are found that match the join condition.
If you're looking for a separate behavior, you may want to think about two separate queries.