I've got the following JPQL :
SELECT a.b.id, a.b.name, a.c.id,a.c.name
left join a.b left join a.c
group by a.b.id,a.b.name,a.c.id,a.c.name
now b and c are both referencing the same table.
the generated SQL is doing the left join I asked, and another join for a.b.name and a.c.name
(which is unnecessary because the left join includes the name, and it retrieves more results than expected)
how do I make the SQL generated not include the unnecessary join?
1 solution came up is not select the names and retrieve them individually by a different query.. but it's not the most elegant way I suppose..
(btw I tried selecting a.b,a.c and group by a.b,a.c but it throws ORA not a group by expression because the generated sql retrieves all rows but group by is only by ID)
and the left join is necessary since I want to allow null values.
Thanks a lot.
SELECT a.b.id, a.b.name, a.c.id,a.c.name
The above implicitly creates an inner join between a abd b,a nd another inner join between a and c. The query should be
select b.id, b.name, c.id, c.name
from A a
left join a.b b
left join a.c c
The group by clause doesn't make any sense, since you have no aggregate in your select clause. group by would be useful if you had, for example
select b.id, b.name, c.id, c.name, count(c.foo)
from A a
left join a.b b
left join a.c c
group by b.id, b.name, c.id, c.name
Related
There is an example request in which there are several joins.
SELECT DISTINCT ON(a.id_1) 1, a.name, b.task, c.created_at
FROM a
INNER JOIN b ON a.id_2 = b.id
INNER JOIN c ON a.ID_2 = c.id
WHERE a.deleted_at IS NULL
ORDER BY a.id_1 desc
In this case, the query will work, sorting by unique values of id_1 will take place. But I need to sort by the column a.name. In this case, postresql will swear with the words ERROR: SELECT DISTINCT ON expressions must match initial ORDER BY expressions.
The following query can serve as a solution to the problem:
SELECT *
FROM(
SELECT DISTINCT ON(a.id_1) a.name, b.task, c.created_at
FROM a
INNER JOIN b ON a.id_2 = b.id
INNER JOIN c ON a.ID_2 = c.id
WHERE a.deleted_at IS NULL
)
ORDER_BY a.name desc
But in reality the database is very large and such a query is not optimal. Are there other ways to sort by the selected column while keeping one uniqueness?
What's the difference between
SELECT COUNT(*)
FROM TOOL T
LEFT OUTER JOIN PREVENT_USE P ON T.ID = P.TOOL_ID
WHERE
P.ID IS NULL
and
SELECT COUNT(*)
FROM TOOL T
LEFT OUTER JOIN PREVENT_USE P ON T.ID = P.TOOL_ID AND P.ID IS NULL
?
The bottom query is equivalent to
SELECT COUNT(*)
FROM TOOL T
since it is not limiting the result set but rather producing a joined table with a lot of null fields for the right part of the join.
The first query is a left anti join.
This is the query when I run this it gives me duplicate records but I remove the INNER JOIN planingOrderBookHeader PLOH ON sd.StyleID=PLOH.StyleID and the column PLOH.OderBookID, it gives records without duplicating but I need records with column name PLOH.OderBookID how can I solve this problem ?
SELECT
CPO.ID
,CPO.StyleID
,cpo.CustomerPo
,PLOH.OderBookID
,cpo.Process
,CPD.Qty
,cpd.RefID
,cpd.Uom
,UM.MeshType
,PRC.Name
,STC.NewStyleno
,SD.TypeID
,itm.Name Part
,SD.ColorID
,COL.Name Color
,SD.FabricID
,FAB.Name Faric
,SHD.ItemID
,ITD.Name Item
,SHD.Image
FROM CustomerPO_Header CPO
INNER JOIN styleconfirmHeader STC ON STC.StyleID=CPO.StyleID
INNER JOIN CustomerPo_Details CPD ON CPO.ID=CPD.CusPOHeaderID
INNER JOIN StyleHeader SHD ON SHD.StyleID=CPO.StyleID
INNER JOIN StyleDetails SD ON CPO.StyleID=SD.StyleID
INNER JOIN ItemDetails itm ON SD.TypeID=itm.ID
INNER JOIN ColorDetails COL ON SD.ColorID=COL.ID
INNER JOIN ItemFabricDetails FAB ON FAB.ID=SD.FabricID
INNER JOIN UOM UM ON Um.ID=CPD.Uom
INNER JOIN ItemTypeDetails ITD ON SHD.ItemID=ITD.ID
INNER JOIN process PRC ON PRC.ID=CPO.Process
INNER JOIN planingOrderBookHeader PLOH ON sd.StyleID=PLOH.StyleID
Plz help me
It's hard to test without knowing what data you have. However you could try moving the table that is causing your duplicates into a subquery instead of a join. so something like:
SELECT
CPO.ID
,CPO.StyleID
,cpo.CustomerPo
,(SELECT PLOH.OderBookID FROM planingOrderBookHeader PLOH WHERE sd.StyleID=PLOH.StyleID) AS OderBookID
,cpo.Process
,CPD.Qty
,cpd.RefID
,cpd.Uom
,UM.MeshType
,PRC.Name
,STC.NewStyleno
,SD.TypeID
,itm.Name Part
,SD.ColorID
,COL.Name Color
,SD.FabricID
,FAB.Name Faric
,SHD.ItemID
,ITD.Name Item
,SHD.Image
FROM CustomerPO_Header CPO
INNER JOIN styleconfirmHeader STC ON STC.StyleID=CPO.StyleID
INNER JOIN CustomerPo_Details CPD ON CPO.ID=CPD.CusPOHeaderID
INNER JOIN StyleHeader SHD ON SHD.StyleID=CPO.StyleID
INNER JOIN StyleDetails SD ON CPO.StyleID=SD.StyleID
INNER JOIN ItemDetails itm ON SD.TypeID=itm.ID
INNER JOIN ColorDetails COL ON SD.ColorID=COL.ID
INNER JOIN ItemFabricDetails FAB ON FAB.ID=SD.FabricID
INNER JOIN UOM UM ON Um.ID=CPD.Uom
INNER JOIN ItemTypeDetails ITD ON SHD.ItemID=ITD.ID
INNER JOIN process PRC ON PRC.ID=CPO.Process
Of course this may have performance implications.
I want to only return the row where the count(object) is the highest, so I have written this query
select klantnr, count(objectnaam)
from klanten inner join deelnames using(klantnr)
inner join reizen using(reisnr)
inner join bezoeken using(reisnr)
where objectnaam = 'Maan'
group by klantnr
Now, I can't do
select max(count(objectnaam))
How would I go about solving this problem?
I have tried by using a subquery which is equally invalid
select max(select count(objectnaam) from ....)
I think I need a subquery in the from, so I have rewritten the query like this which I think is closer to the actual answer but still not right, as now it returns the maximum value of all rows.
select klantnr, max(c)
FROM(
select klantnr, count(objectnaam) as c
from klanten inner join deelnames using(klantnr)
inner join reizen using(reisnr)
inner join bezoeken using(reisnr)
where objectnaam = 'Maan'
group by klantnr) as F
group by klantnr
thanks for any help you can give me!
You do not provide the structure of tables, so probably you have to modify the following query. However it works just for PostgreSQL 9.x+
WITH t AS (
SELECT klantnr, COUNT(objectnaam) AS c
FROM klanten
WHERE objectnaam = 'Maan'
GROUP BY klantnr
ORDER BY c DESC
LIMIT 1
)
SELECT * FROM t
INNER JOIN deelnames USING(klantnr)
INNER JOIN reizen USING(reisnr)
INNER JOIN bezoeken USING(reisnr);
see http://www.postgresql.org/docs/9.3/static/queries-with.html how to use WITH QUERIES.
I have found a simpeler solution:
select klantnr,count (klantnr)
from bezoeken natural join deelnames
where objectnaam ='Maan'
group by klantnr
order by count desc
limit 1
I have a stored procedure which is running quite slow. Therefore I want to extract some of the query in a separate view.
My code looks something like this:
DECLARE #tmpTable TABLE(..)
INSERT INTO #tmpTable (..) *query* (returns 3000 rows)
Select ... from table1
inner join table2
inner join table3
inner join #tmpTable
...
I then extract (copy-paste) the *query* and put it in a view - i.e. vView.
Doing this will then give me a different result:
Select ... from table1
inner join table2
inner join table3
inner join vView
...
Why? I can see that the vView and the #tmpTable both returns 3000 rows, so they should match (also did a except query to check).
Any comments would be much appriciated as I feel quite stuck with this..
EDITED:
This is the full query for getting the result (using #tmpTable or vView gives me different results, although the appear the same):
select dep.sid as depsid, dep.[name], COUNT(b.sid) as possiblelogins, count(ls.clientsid) as logins
from department dep
inner join relationship r on dep.sid=r.primarysid and r.relationshiptypeid=27 and r.validto is null
inner join [user] u on r.secondarysid=u.sid
inner join relationship r2 on u.sid=r2.secondarysid and r2.validto is null and r2.relationshiptypeid in (1,37)
inner join client c on r2.primarysid=c.sid
inner join ***#tmpTable or vView*** b on b.sid = c.sid
left outer join (select distinct clientsid from logonstatistics) as ls on b.sid=ls.clientsid
GROUP BY dep.sid, dep.[name],dep.isdepartment
HAVING dep.isdepartment=1
You maybe don't need the view/table if you change to this.
It joins on to client c and appears to be there only to JOIN onto logonstatistics
--remove inner join ***#tmpTable or vView*** b on b.sid = c.sid
--change JOIN
left outer join (select distinct clientsid from logonstatistics) as ls on c.sid=ls.clientsid
And change COUNT(b.sid) to COUNT(c.sid) in the SELECT clause
Otherwise, if you get different results you have two options I can see:
Table and view have different data. Have you run a line by line comparsion?
One has NULL, one has a value (especially for the sid column which will affect the JOIN)
Finally, when you says "different results" do you mean you get x2 or x3 rows? A different COUNT? What?