I was wondering what the answer should be for 1c. on this website:
http://sqlzoo.net/6.htm
SELECT company
FROM route WHERE stop=4
GROUP BY name, ID
this obviously isn't working, the ID and name isn't showing up no matter what. What is missing here? Thanks.
SELECT stops.id, stops.name
FROM route
INNER JOIN stops on route.stop = stops.id
WHERE route.num = 4 AND route.company = 'LRT'
You need to join the tables as the data you want to return is in a different table to the one which filters the data.
This works and does not include any unnecessary table joins. A good rule of thumb is to use EXISTS to verify values in a table that you do not need the output for. Otherwise, you would use a JOIN
SELECT stops.id, stops.name
FROM stops
WHERE EXISTS
(
SELECT 1 FROM route
WHERE route.stop = stops.id AND num = '4' AND company = 'LRT'
)
select s.id, s.name
from stops s
inner join route r
on s.id = r.stop
where r.num= 4
AND r.company= 'LRT'
It gives you this error:
sql: Unknown column 'name' in 'group statement'
There is no name in route tabel.
The tables structure are:
stops(id, name)
route(num,company,pos, stop)
So the answer for this quiz is:
SELECT s.id, s.name
FROM route r, stops s
WHERE r.stop= s.id
and r.num = 4 AND r.company = 'LRT'
Related
Adding back some original info for historical purposes as I thought simplifying would help but it didn't. We have this stored procedure, in this part it is selecting records from table A (calldetail_reporting_agents) and doing a left join on table B (Intx_Participant). Apparently there are duplicate rows in table B being pulled that we DON'T want. Is there any easy way to change this up to only pick the first match on table B? Or will I need to rewrite the whole thing?
SELECT 'Agent Calls' AS CallType,
CallDate,
CallTime,
RemoteNumber,
DialedNumber,
RemoteName,
LocalUserId,
CallDurationSeconds,
Answered,
AnswerSpeed,
InvalidCall,
Intx_Participant.Duration
FROM calldetail_reporting_agents
LEFT JOIN Intx_Participant ON calldetail_reporting_agents.CallID = Intx_Participant.CallIDKey
WHERE DialedNumber IN ( SELECT DialedNumber
FROM #DialedNumbers )
AND ConnectedDate BETWEEN #LocStartDate AND #LocEndDate
AND (#LocQueue IS NULL OR AssignedWorkGroup = #LocQueue)
Simpler version: how to change below to select only first matching row from table B:
SELECT columnA, columnB FROM TableA LEFT JOIN TableB ON someColumn
I changed to this per the first answer and all data seems to look exactly as expected now. Thank you to everyone for the quick and attentive help.
SELECT 'Agent Calls' AS CallType,
CallDate,
CallTime,
RemoteNumber,
DialedNumber,
RemoteName,
LocalUserId,
CallDurationSeconds,
Answered,
AnswerSpeed,
InvalidCall,
Intx_Participant.Duration
FROM calldetail_reporting_agents
OUTER APPLY (SELECT TOP 1
*
FROM Intx_Participant ip
WHERE calldetail_reporting_agents.CallID = ip.CallIDKey
AND calldetail_reporting_agents.RemoteNumber = ip.ConnValue
AND ip.HowEnded = '9'
AND ip.Recorded = '0'
AND ip.Duration > 0
AND ip.Role = '1') Intx_Participant
WHERE DialedNumber IN ( SELECT DialedNumber
FROM #DialedNumbers )
AND ConnectedDate BETWEEN #LocStartDate AND #LocEndDate
AND (#LocQueue IS NULL OR AssignedWorkGroup = #LocQueue)
You can try to OUTER APPLY a subquery getting only one matching row.
...
FROM calldetail_reporting_agents
OUTER APPLY (SELECT TOP 1
*
FROM intx_Participant ip
WHERE ip.callidkey = calldetail_reporting_agents.callid) intx_participant
WHERE ...
You should add an ORDER BY in the subquery. Otherwise it isn't deterministic which row is taken as the first. Or maybe that's not an issue.
I have to join two different table to get my result.
The table 'Resource' it is simple, while the table 'Dimension.[Code]' contains, among the others, a column with different values (i.e :
Code
SILO
GRADE
OTHER 1
OTHER2
This is the reason why a join twice that column to get two different columns called GRADE and SILO.
Now, I have a query that selects the maximum value of a grade within the group as follows:
`SELECT
R.[ID] -- If I inserted that here, it is not working obviously.
-- This cannot But this is the additional column I need (see later)
DD_SILO.[Value] DIR ,
max(R.[GRADE]) GRADE_DIR
FROM [Resource] R
LEFT JOIN
Dimension DD_SILO ON R.[ID] = DD_SILO.[ID] AND DD_SILO.[Code] = 'SILO'
group by DD_SILO.[Value]'
What I need is basically to have, beside GRADE AND SILO, also the ID name, which is contained into the [Resource] table.
Please notice that [Resource].ID = [Dimension].ID
I would have solved the problem with ROW_NUMBER () to select the highest within the group, avoiding then then 'group by', but as the query has to be inserted in a bigger one, that would take too much time to run. I am using Microsoft SQL Server 2016.
Could you use a virtual table something like: -
`
select
a.max_grade_silo,
a.max_grade_value,
(select max(r.id)
from [resource] r,
[dimension] d
where r.[ID] = d.[ID] and
d.[CODE]= 'SILO' and
r.[GRADE] = a.[max_grade_value]
),
max_grade_silo a
from
(SELECT
DD_SILO.[Value] DIR ,
max(R.[GRADE]) GRADE_DIR
FROM [Resource] R
LEFT JOIN
Dimension DD_SILO ON R.[ID] = DD_SILO.[ID] AND DD_SILO.[Code] = 'SILO'
group by DD_SILO.[Value]
) temp_result (max_grade_silo, max_grade_value)
'
Probably better to look at normalizing the tables?
SELECT
MAX(R.[ID]) as ID ,
DD_SILO.[Value] DIR ,
max(R.[GRADE]) GRADE_DIR
FROM [Resource] R
LEFT JOIN
Dimension DD_SILO ON R.[ID] = DD_SILO.[ID] AND DD_SILO.[Code] = 'SILO'
group by DD_SILO.[Value]
I have a table that represents an Object. It has many columns but also fields that require language support.
For simplicity let's say I have 3 tables:
MainObjectTable
LanguageDependantField1
LanguageDependantField2.
MainObjectTable has a PK int called ID, and both LanguageDependantTables have a foreign key link back to the MainObjectTable along with a language code and the date they were added.
I've created a stored procedure that accepts the MainObjectTable ID and a Language. It will return a single row containing the most recent items from the language tables. The select statement looks like
SELECT
MainObjectTable.VariousColumns,
LanguageDependantField1.Description,
LanguageDependantField2.SomeOtherText
FROM
MainObjectTable
OUTER APPLY
(SELECT TOP 1 LanguageDependantField1.Description
FROM LanguageDependantField1
WHERE LanguageDependantField1.MainObjectTable_ID = MainObjectTable.ID
AND LanguageDependantField1.Language_ID = #language
ORDER BY
LanguageDependantField1.[Default], LanguageDependantField1.CreatedDate DESC) LanguageDependantField1
OUTER APPLY
(SELECT TOP 1 LanguageDependantField2.SomeOtherText
FROM LanguageDependantField2
WHERE LanguageDependantField2.MainObjectTable_ID = MainObjectTable.ID
AND LanguageDependantField2.Language_ID = #language
ORDER BY
LanguageDependantField2.[Default] DESC, LanguageDependantField2.CreatedDate DESC) LanguageDependantField2
WHERE
MainObjectTable.ID = #MainObjectTableID
What I want to add is the ability to fallback to a default language if a row isn't found in the specified language. Let's say we use "German" as the selected language. Is it possible to return an English row from LanguageDependantField1 if the German does not exist presuming we have #fallbackLanguageID
Also am I right to use OUTER APPLY in this scenario or should I be using JOIN?
Many thanks for your help.
Try this:
SELECT MainObjectTable.VariousColumns,
COALESCE(PrefLang.Description,Fallback.Description,'Not Found Desc')
as Description,
COALESCE(PrefLang.SomeOtherText,FallBack.SomeOtherText,'Not found')
as SomeOtherText
FROM MainObjectTable
LEFT JOIN
(SELECT TOP 1 pl.Description,pl.SomeOtherText
FROM LanguageDependantField1 pl
WHERE pl.MainObjectTable_ID = MainObjectTable.ID
AND pl.Language_ID = #language
ORDER BY
pl.[Default], pl.CreatedDate DESC)
PrefLang ON 1=1
LEFT JOIN
(SELECT TOP 1 fb.Description,fb.SomeOtherText
FROM LanguageDependantField1 fb
WHERE fb.MainObjectTable_ID = MainObjectTable.ID
AND fb.Language_ID = #fallbackLanguageID
ORDER BY
fb.[Default], fb.CreatedDate DESC)
Fallback ON 1=1
WHERE
MainObjectTable.ID = #MainObjectTableID
Basically, make two queries, one to the preferred language and one to English (Default). Use the LEFT JOIN, so if the first one isn't found, the second query is used...
I don't have your actual tables, so there might be a syntax error in above, but hope it gives you the concept you want to try...
Yes, the use of Outer Apply is correct if you want to correlate the MainObjectTable table rows to the inner queries. You cannot use Joins with references in the derived table to the outer table. If you wanted to use Joins, you would need to include the joining column(s) and in this case pre-filter the results. Here is what that might look like:
With RankedLanguages As
(
Select LDF1.MainObjectTable_ID, LDF1.Language_ID, LDF1.Description, LDF1.SomeOtherText, ...
, Row_Number() Over ( Partition By LDF1.MainObjectTable_ID, LDF1.Language_ID
Order By LDF1.[Default] Desc, LDF1.CreatedDate Desc ) As Rnk
From LanguageDependantField1 As LDF1
Where LDF1.Language_ID In( #languageId, #defaultLanguageId )
)
Select M.VariousColumns
, Coalesce( SpecificLDF.Description, DefaultLDF.Description ) As Description
, Coalesce( SpecificLDF.SomeOtherText, DefaultLDF.SomeOtherText ) As SomeOtherText
, ...
From MainObjectTable As M
Left Join RankedLanguages As SpecificLDF
On SpecificLDF.MainObjectTable_ID = M.ID
And SpecifcLDF.Language_ID = #languageId
And SpecifcLDF.Rnk = 1
Left Join RankedLanguages As DefaultLDF
On DefaultLDF.MainObjectTable_ID = M.ID
And DefaultLDF.Language_ID = #defaultLanguageId
And DefaultLDF.Rnk = 1
Where M.ID = #MainObjectTableID
I am new to PostgreSQL and I have a problem with the following query:
WITH relevant_einsatz AS (
SELECT einsatz.fahrzeug,einsatz.mannschaft
FROM einsatz
INNER JOIN bergefahrzeug ON einsatz.fahrzeug = bergefahrzeug.id
),
relevant_mannschaften AS (
SELECT DISTINCT relevant_einsatz.mannschaft
FROM relevant_einsatz
WHERE relevant_einsatz.fahrzeug IN (SELECT id FROM bergefahrzeug)
)
SELECT mannschaft.id,mannschaft.rufname,person.id,person.nachname
FROM mannschaft,person,relevant_mannschaften WHERE mannschaft.leiter = person.id AND relevant_mannschaften.mannschaft=mannschaft.id;
This query is working basically - but in "relevant_mannschaften" I am currently selecting each mannschaft, which has been to an relevant_einsatz with at least 1 bergefahrzeug.
Instead of this, I want to select into "relevant_mannschaften" each mannschaft, which has been to an relevant_einsatz WITH EACH from bergefahrzeug.
Does anybody know how to formulate this change?
The information you provide is rather rudimentary. But tuning into my mentalist skills, going out on a limb, I would guess this untangled version of the query does the job much faster:
SELECT m.id, m.rufname, p.id, p.nachname
FROM person p
JOIN mannschaft m ON m.leiter = p.id
JOIN (
SELECT e.mannschaft
FROM einsatz e
JOIN bergefahrzeug b ON b.id = e.fahrzeug -- may be redundant
GROUP BY e.mannschaft
HAVING count(DISTINCT e.fahrzeug)
= (SELECT count(*) FROM bergefahrzeug)
) e ON e.mannschaft = m.id
Explain:
In the subquery e I count how many DISTINCT mountain-vehicles (bergfahrzeug) have been used by a team (mannschaft) in all their deployments (einsatz): count(DISTINCT e.fahrzeug)
If that number matches the count in table bergfahrzeug: (SELECT count(*) FROM bergefahrzeug) - the team qualifies according to your description.
The rest of the query just fetches details from matching rows in mannschaft and person.
You don't need this line at all, if there are no other vehicles in play than bergfahrzeuge:
JOIN bergefahrzeug b ON b.id = e.fahrzeug
Basically, this is a special application of relational division. A lot more on the topic under this related question:
How to filter SQL results in a has-many-through relation
Do not know how to explain it, but here is an example how I solved this problem, just in case somebody has the some question one day.
WITH dfz AS (
SELECT DISTINCT fahrzeug,mannschaft FROM einsatz WHERE einsatz.fahrzeug IN (SELECT id FROM bergefahrzeug)
), abc AS (
SELECT DISTINCT mannschaft FROM dfz
), einsatzmannschaften AS (
SELECT abc.mannschaft FROM abc WHERE (SELECT sum(dfz.fahrzeug) FROM dfz WHERE dfz.mannschaft = abc.mannschaft) = (SELECT sum(bergefahrzeug.id) FROM bergefahrzeug)
)
SELECT mannschaft.id,mannschaft.rufname,person.id,person.nachname
FROM mannschaft,person,einsatzmannschaften WHERE mannschaft.leiter = person.id AND einsatzmannschaften.mannschaft=mannschaft.id;
This is probably a stupid question to most of you but I was wondering whether you can rename a column using the 'AS' keyword and a select statement?
Here is my SQL:
Select Main.EmpId
, Associate_List.costCenter, Assignments.Area
, Main.Assignments_1 AS (
Select Assignment_Name
from Assignments
where Assignment_Number = 1
and Assignments.Area = '#Someparemeter'
)
from associate_list
, main
, APU_CC
, Assignments
where Main.Empid = Associate_List.Empid
and substring(Associate_List.CostCenter,1,4) = APU_CC.CostCentre
The only part of SQL I'm wondering about is:
Main.Assignments_1 AS (
Select Assignment_Name
from Assignments
where Assignment_Number = 1
and Assignments.Area = '#Someparemeter'
)
Is this possible or am I talking jibberish or is this just a stupid thing to do?
Many Thanks
The part after as is not a value but a variable name; the SQL database will use it to reference the value of the result set so you can compare/sort/filter them. Therefore this is not possible.
If you must do this, you must read the documentation of your database how to build dynamic queries. But I suggest against it because it will cause strange errors that will be very hard to debug.
I'm not quite sure what you are driving at.
If there is a column in the Main table called Assignments_1, you can rename it in your query (to give a different header at the top of the output or for some other reason) like this...
SELECT MAIN.ASSIGNMENT_1 AS MY_NEW_NAME
FROM etc.
If you want a derived table in your query you name it like this...
SELECT MAIN.ASSIGNMENT_1,
SELECT *
FROM (SELECT THIS, THAT, THE_OTHER
FROM SOME_TABLE) AS DERIVED_TABLE
FROM etc.
If you didn't want either of those things, please clarify and we'll try to help.
In SQL Server, you can assign an alias to a column with AS like so:
...
ColumnName AS ColumnAlias,
...
And you can do it for a "sub-select" like you have in your example. (I wouldn't write the query quite like that--I'd run the subquery first and then plop the result into the second query like so:
DECLARE #Assignment_Name varca(100) -- or however long
SELECT #Assignment_Name = Assignment_Name
from Assignments
where Assignment_Number = 1
and Assignments.Area = #Someparemeter
SELECT
...
#Assignment_Name = Assignment_Name,
...
But you can do this:
Select m.EmpId, l.costCenter,
(Select Area From Assignments a
Where Assignment_Number = 1
And Area = '#Someparemeter') As Area,
(Select Assignment_Name From Assignments a
Where Assignment_Number = 1
And Area = '#Someparemeter') As Assignments_1
From associate_list l
Join main m On m.Empid = l.Empid
Join APU_CC c On c.CostCentre = substring(l.CostCenter,1,4)
or this:
Select m.EmpId, l.costCenter, Asgn.Area,
Asgn.Assignment_Name as Assignments_1
From associate_list l
Join main m On m.Empid = l.Empid
Join APU_CC c On c.CostCentre = substring(l.CostCenter,1,4)
Cross Join (Select Assignment_Name From Assignments a
Where Assignment_Number = 1
And Area = '#Someparemeter') as Asgn