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;
Related
I have the following SQL
WITH tally AS (
SELECT results.answer,
results.poll_id,
count(1) AS votes
FROM (
SELECT pr.poll_id,
unnest(pr.response) AS answer
FROM poll_responses pr
LEFT JOIN polls p ON pr.poll_id = p.id
LEFT JOIN poll_collections pc ON pc.id = p.poll_collection_id
WHERE pc.id = ${pollCollectionId}
) AS results
GROUP BY results.answer, results.poll_id
),
all_choices AS (SELECT unnest(pls.choices) AS choice,
pls.id AS poll_id
FROM poll_collections pcol
INNER JOIN polls pls
ON pcol.id = pls.poll_collection_id
WHERE pcol.id = ${pollCollectionId}),
unvoted_tally AS (SELECT ac.choice AS answer,
ac.poll_id,
0 AS total
FROM all_choices ac
LEFT JOIN tally t ON t.answer = ac.choice
WHERE t.answer IS NULL),
final_tally AS (SELECT *
FROM tally
UNION
ALL
SELECT *
FROM unvoted_tally),
sorted_tally AS (
SELECT ft.*
FROM final_tally ft
ORDER BY array_position(array(SELECT choice FROM all_choices), ft.answer)
)
SELECT json_agg(poll_results.polls) AS polls
FROM (
SELECT json_array_elements(json_agg(results)) -> 'poll' AS polls
FROM (
SELECT json_build_object(
'id', st.poll_id,
'question', pls.question,
'choice-type', pls.choice_type,
'results',
json_agg(json_build_object('choice', st.answer, 'votes', st.votes)),
'chosen', pr.response
) AS poll
FROM sorted_tally st
LEFT JOIN polls pls
ON
pls.id = st.poll_id
LEFT JOIN poll_responses pr
ON
pr.poll_id = st.poll_id AND
pr.email = ${email}
GROUP BY st.poll_id, pls.choice_type, pr.response, pls.question
) AS results)
AS poll_results;
I have a poll_responses table which store the user responses of a poll. I want to order the responses in exactly the same order they are stored in the polls table - as an array e.g., {Yes, No, Maybe}.
I applied the ORDER BY array_position(array(SELECT choice FROM all_choices), ft.answer) in the sorted_tally CTE.
However, in the file SELECT after applying GROUP BY the order is lost.
Is there a way to preserve the order of the choices?
Also, are there any optimizations applicable?
Much appreciated!
In json_build_object or json_agg you can set ORDER BY clause. First, have the last CTE SELECT needed order expression as a new column, then run in outermost query:
CTE
...
sorted_tally AS (
SELECT ft.votes
, ft.poll_id
, ft.answer
, array_position(array(SELECT choice FROM all_choices),
ft.answer) AS choice_order
FROM final_tally ft
ORDER BY
)
Outermost Query
...
json_build_object(
'id', st.poll_id,
'question', pls.question,
'choice-type', pls.choice_type,
'results', json_agg(json_build_object('choice', st.answer,
'votes', st.votes)
ORDER BY st.choice_order),
'chosen', pr.response
) AS poll
ORDER BY in a CTE doesn't really matter. It may work, but SQL Server is free to re-order the rows unless you specify ORDER BY in the outermost query to order all the results.
I have three tables:
Plans(PlanID(key), Capacity)
CustomerInProject(VahedID, cinpid(key))
Vahed(VahedID(key), PlanID,...)
This query shows number of houses with the same PlanID (map) that people hired:
select
count(*)
from
Vahed as v2,
CustomerInProject
where
CustomerInProject.VahedID = v2.VahedID
group by PlanID
Plans has an int field named Capacity. I want to subtract Capacity from the above query. How can I do that?
Something like this should do it:
select p.PlanID, count(*) - p.Capacity
from Vahed as v2
join CustomerInProject c
on c.VahedID = v2.VahedID
join Plan p
on p.PlanID = c.PlanID /* or v.PlanID, it's not clear from the question */
group by p.PlanID, p.Capacity
On the 6th line, you may want to replace c.PlanID with v.PlanID - I don't know the exact table schema.
select sum(cnt)
from
(select capacity*-1 as cnt from
plans
union
select count(*) as cnt from Vahed as v2
inner join
CustomerInProject on
CustomerInProject.VahedID = v2.VahedID
group by PlanID )
I have a SQL Server 2005 query that I'm trying to assemble right now but I am having some difficulties.
I have a group by clause based on 5 columns: Project, Area, Name, User, Engineer.
Engineer is coming from another table and is a one to many relationship
WITH TempCTE
AS (
SELECT htce.HardwareProjectID AS ProjectId
,area.AreaId AS Area
,hs.NAME AS 'Status'
,COUNT(*) AS Amount
,MAX(htce.DateEdited) AS DateModified
,UserEditing AS LastModifiedName
,Engineer
,ROW_NUMBER() OVER (
PARTITION BY htce.HardwareProjectID
,area.AreaId
,hs.NAME
,htce.UserEditing ORDER BY htce.HardwareProjectID
,Engineer DESC
) AS row
FROM HardwareTestCase_Execution AS htce
INNER JOIN HardwareTestCase AS htc ON htce.HardwareTestCaseID = htc.HardwareTestCaseID
INNER JOIN HardwareTestGroup AS htg ON htc.HardwareTestGroupID = htg.HardwareTestGroupId
INNER JOIN Block AS b ON b.BlockId = htg.BlockId
INNER JOIN Area ON b.AreaId = Area.AreaId
INNER JOIN HardwareStatus AS hs ON htce.HardwareStatusID = hs.HardwareStatusId
INNER JOIN j_Project_Testcase AS jptc ON htce.HardwareProjectID = jptc.HardwareProjectId AND htce.HardwareTestCaseID = jptc.TestcaseId
WHERE (htce.DateEdited > #LastDateModified)
GROUP BY htce.HardwareProjectID
,area.AreaId
,hs.NAME
,htce.UserEditing
,jptc.Engineer
)
The gist of what I want is to be able to deal with empty Engineer columns. I don't want this column to have a blank second entry (where row=2).
What I want to do:
Group the items with "row" value of 1 & 2 together.
Select the Engineer that isn't empty.
Do not deselect engineers where there is not a matching row=2.
I've tried a series of joins to try and make things work. No luck so far.
Use j_Project_Testcase PIVOT( MAX(Engineer) for Row in ( [1], [2] ) then select ISNULL( [1],[2]) to select the Engineer value
I can give you a more robust example if you set up a SQL fiddle
Try reading this: PIVOT and UNPIVOT
I'm trying to make a query to retrieve the region which got the most sales for sweet products. 'grupo_produto' is the product type, and 'regiao' is the region. So I got this query:
SELECT TOP 1 r.nm_regiao, (SELECT COUNT(*)
FROM Dw_Empresa
WHERE grupo_produto='1' AND
cod_regiao = d.cod_regiao) as total
FROM Dw_Empresa d
INNER JOIN tb_regiao r ON r.cod_regiao = d.cod_regiao ORDER BY total DESC
Then when i run the query, MS-Access asks for the "total" parameter. Why it doesn't consider the newly created 'column' I made in the select clause?
Thanks in advance!
Old Question I know, but it may help someone knowing than while you cant order by aliases, you can order by column index. For example, this will work without error :
SELECT
firstColumn,
IIF(secondColumn = '', thirdColumn, secondColumn) As yourAlias
FROM
yourTable
ORDER BY
2 ASC
The results would then be ordered by the values found in the second column wich is the Alias "yourAlias".
Aliases are only usable in the query output. You can't use them in other parts of the query. Unfortunately, you'll have to copy and paste the entire subquery to make it work.
You can do it like this
select * from(
select a + b as c, * from table)
order by c
Access has some differences compared to Sql Server.
Why it doesn't consider the newly
created 'column' I made in the select
clause?
Because Access (ACE/Jet) is not compliant with the SQL-92 Standard.
Consider this example, which is valid SQL-92:
SELECT a AS x, c - b AS y
FROM MyTable
ORDER
BY x, y;
In fact, x and y the only valid elements in the ORDER BY clause because all others are out of scope (ordinal numbers of columns in the SELECT clause are valid though their use id deprecated).
However, Access chokes on the above syntax. The equivalent Access syntax is this:
SELECT a AS x, c - b AS y
FROM MyTable
ORDER
BY a, c - b;
However, I understand from #Remou's comments that a subquery in the ORDER BY clause is invalid in Access.
Try using a subquery and order the results in an outer query.
SELECT TOP 1 * FROM
(
SELECT
r.nm_regiao,
(SELECT COUNT(*)
FROM Dw_Empresa
WHERE grupo_produto='1' AND cod_regiao = d.cod_regiao) as total
FROM Dw_Empresa d
INNER JOIN tb_regiao r ON r.cod_regiao = d.cod_regiao
) T1
ORDER BY total DESC
(Not tested.)
How about:
SELECT TOP 1 r.nm_regiao
FROM (SELECT Dw_Empresa.cod_regiao,
Count(Dw_Empresa.cod_regiao) AS CountOfcod_regiao
FROM Dw_Empresa
WHERE Dw_Empresa.[grupo_produto]='1'
GROUP BY Dw_Empresa.cod_regiao
ORDER BY Count(Dw_Empresa.cod_regiao) DESC) d
INNER JOIN tb_regiao AS r
ON d.cod_regiao = r.cod_regiao
I suggest using an intermediate query.
SELECT r.nm_regiao, d.grupo_produto, COUNT(*) AS total
FROM Dw_Empresa d INNER JOIN tb_regiao r ON r.cod_regiao = d.cod_regiao
GROUP BY r.nm_regiao, d.grupo_produto;
If you call that GroupTotalsByRegion, you can then do:
SELECT TOP 1 nm_regiao, total FROM GroupTotalsByRegion
WHERE grupo_produto = '1' ORDER BY total DESC
You may think it's extra work to create the intermediate query (and, in a sense, it is), but you will also find that many of your other queries will be based off of GroupTotalsByRegion. You want to avoid repeating that logic in many other queries. By keeping it in one view, you provide a simplified route to answering many other questions.
How about use:
WITH xx AS
(
SELECT TOP 1 r.nm_regiao, (SELECT COUNT(*)
FROM Dw_Empresa
WHERE grupo_produto='1' AND
cod_regiao = d.cod_regiao) as total
FROM Dw_Empresa d
INNER JOIN tb_regiao r ON r.cod_regiao = d.cod_regiao
) SELECT * FROM xx ORDER BY total
I'm having this Mysql query, It works:
SELECT
nom
,prenom
,(SELECT GROUP_CONCAT(category_en) FROM
(SELECT DISTINCT category_en FROM categories c WHERE id IN
(SELECT DISTINCT category_id FROM m3allems_to_categories m2c WHERE m3allem_id = 37)
) cS
) categories
,(SELECT GROUP_CONCAT(area_en) FROM
(SELECT DISTINCT area_en FROM areas c WHERE id IN
(SELECT DISTINCT area_id FROM m3allems_to_areas m2a WHERE m3allem_id = 37)
) aSq
) areas
FROM m3allems m
WHERE m.id = 37
The result is:
nom prenom categories areas
Man Multi Carpentry,Paint,Walls Beirut,Baalbak,Saida
It works correclty, but only when i hardcode into the query the id that I want (37).
I want it to work for all entries in the m3allem table, so I try this:
SELECT
nom
,prenom
,(SELECT GROUP_CONCAT(category_en) FROM
(SELECT DISTINCT category_en FROM categories c WHERE id IN
(SELECT DISTINCT category_id FROM m3allems_to_categories m2c WHERE m3allem_id = m.id)
) cS
) categories
,(SELECT GROUP_CONCAT(area_en) FROM
(SELECT DISTINCT area_en FROM areas c WHERE id IN
(SELECT DISTINCT area_id FROM m3allems_to_areas m2a WHERE m3allem_id = m.id)
) aSq
) areas
FROM m3allems m
And I get an error:
Unknown column 'm.id' in 'where
clause'
Why?
From the MySql manual:
13.2.8.7. Correlated Subqueries
[...]
Scoping rule: MySQL evaluates from inside to outside.
So... do this not work when the subquery is in a SELECT section? I did not read anything about that.
Does anyone know? What should I do? It took me a long time to build this query... I know it's a monster query but it gets what I want in a single query, and I am so close to getting it to work!
Can anyone help?
You can only correlate one level deep.
Use:
SELECT m.nom,
m.prenom,
x.categories,
y.areas
FROM m3allens m
LEFT JOIN (SELECT m2c.m3allem_id,
GROUP_CONCAT(DISTINCT c.category_en) AS categories
FROM CATEGORIES c
JOIN m3allems_to_categories m2c ON m2c.category_id = c.id
GROUP BY m2c.m3allem_id) x ON x.m3allem_id = m.id
LEFT JOIN (SELECT m2a.m3allem_id,
GROUP_CONCAT(DISTINCT a.area_en) AS areas
FROM AREAS a
JOIN m3allems_to_areas m2a ON m2a.area_id = a.id
GROUP BY m2a.m3allem_id) y ON y.m3allem_id = m.id
WHERE m.id = ?
The reason for the error is that in the subquery m is not defined. It is defined later in the outer query.