How to order after grouping in Rethinkdb like in sql:
select count(id) as cid, ... from x
group by y
order by cid desc
If I properly understood your question, the query you are looking for is (in JavaScript)
r.table("x").group("y").count().ungroup().orderBy("reduction")
In Python/Ruby, it would be
r.table("x").group("y").count().ungroup().order_by("reduction")
Related
I have the following Hibernate HQL query:
select t from Term t join ApprovedCourse ap on t.id = ap.term.id group by t order by t desc
It's failing with the
ORA-00979: not a GROUP BY expression
error because Oracle insists that all select values be in the group by. Hibernate, of course, is hiding the various fields of the Term object from us, letting us deal with it as a Term and not Term.id. (This query works on Postgres, by the way. Postgres is more liberal about its group by requirements.)
Hibernate is producing the following SQL:
select term0_.id as id1_12_, term0_.semester_id as semester_id2_12_, term0_.year_id as year_id3_12_
from term term0_
inner join approved_course approvedco1_
on (term0_.id=approvedco1_.term_id)
group by term0_.id
order by term0_.id desc
I've tried just removing the select t from the start of the query, but then Hibernate assumes that I'm selecting both the Term and ApprovedCourse objects, and that makes things worse.
So how do I make this work in a Hibernate way?
I found that I could get what I want by replacing the group by clause with a distinct in the select clause. Here's the resulting query:
select distinct(t) from Term t join ApprovedCourse ap on t.id = ap.term.id order by t desc
Let me explain the question.
I have two tables, which have 3 columns with same data tpyes. The 3 columns create a key/ID if you like, but the name of the columns are different in the tables.
Now I am creating queries with these 3 columns for both tables. I've managed to independently get these results
For example:
SELECT ID, FirstColumn, sum(SecondColumn)
FROM (SELECT ABC||DEF||GHI AS ID, FirstTable.*
FROM FirstTable
WHERE ThirdColumn = *1st condition*)
GROUP BY ID, FirstColumn
;
SELECT ID, SomeColumn, sum(AnotherColumn)
FROM (SELECT JKM||OPQ||RST AS ID, SecondTable.*
FROM SecondTable
WHERE AlsoSomeColumn = *2nd condition*)
GROUP BY ID, SomeColumn
;
So I make a very similar queries for two different tables. I know the results have a certain number of same rows with the ID attribute, the one I've just created in the queries. I need to check which rows in the result are not in the other query's result and vice versa.
Do I have to make temporary tables or views from the queries? Maybe join the two tables in a specific way and only run one query on them?
As a beginner I don't have any experience how to use results as an input for the next query. I'm interested what is the cleanest, most elegant way to do this.
No, you most probably don't need any "temporary" tables. WITH factoring clause would help.
Here's an example:
with
first_query as
(select id, first_column, ...
from (select ABC||DEF||GHI as id, ...)
),
second_query as
(select id, some_column, ...
from (select JKM||OPQ||RST as id, ...)
)
select id from first_query
minus
select id from second_query;
For another result you'd just switch the tables, e.g.
with ... <the same as above>
select id from second_query
minus
select id from first_query
I have a query like:
select
qsn.code,
(select prs.display_name from prs where prs.id = qsn.fk_prs) display_name,
(select prs.address from prs where prs.id = qsn.fk_prs) address,
(select prs.tel from prs where prs.id = qsn.fk_prs) tel
from
qsn
where
qsn.register_date between :x1 and :x2
When I look at the execution plan of the query, it queries prs table 3 times (each time using INDEX UNIQUE SCAN).
I wonder if I can query the prs table once using WITH clause? How can I write the query that way.
I shall mention that because each of the tables have millions of record, joining them makes the query so slow.
using with clause your query goes like this:
with abc as (select id,
display_name ,
address ,
tel
from prs)
select
qsn.code,
abc.display_name,
abc.address,
abc.tel
from qsn
inner join abc
on qsn.fk_prs = abc.id
where qsn.register_date between :x1 and :x2 ;
ps: not tested.
Use a join:
select qsn.code, prs.display_name, prs.address, prs.tel
from qsn
left join prs on prs.id = qsn.fk_prs
where qsn.register_date between :x1 and :x2
I'm trying to execute a rather simple Oracle query against a table with a XMLTYPE column:
Select POB_CODPOL, CODSIS From (
Select T1.POB_CODPOL, EXTRACTVALUE(T1.POB_XMLPOL, '/Polbas/polfun[nomfun="filterBySystem"]/extpar[codele="codsis"]/valele/text()') CODSIS
From TDTX_POLITICA_CLOB T1
Where T1.POB_CODEMP = '001840'
)
Group By POB_CODPOL, CODSIS
This throws a ORA-00979 Not a GROUP BY Expression, which I don't really understand.
Even worse: when I execute the exact same query, but with a simplified XPATH query does work:
Select POB_CODPOL, CODSIS From (
Select T1.POB_CODPOL, EXTRACTVALUE(T1.POB_XMLPOL, 'Polbas/codpol/text()') CODSIS
From TDTX_POLITICA_CLOB T1
Where T1.POB_CODEMP = '001840'
)
Group By POB_CODPOL, CODSIS
It looks like Oracle doesn't like conditions like [nomfun="filterBySystem"] when using a GROUP BY (without the grouping clause, everything works fine).
Any idea on why this can be happening?
Edit: the result of the inner query is rather simple:
EXTRACTVALUE is deprecated.
Oracle recommends to use XMLQUERY, XMLTABLE for it.
This one should work:
WITH t as
(SELECT T1.POB_CODPOL, x.CODSIS
FROM TDTX_POLITICA_CLOB T1
NATURAL JOIN XMLTABLE('/Polbas/polfun[nomfun="filterBySystem"]/extpar[codele="codsis"]/valele'
PASSING POB_XMLPOL COLUMNS
CODSIS VARCHAR2(50) PATH '/') x
Where T1.POB_CODEMP = '001840')
SELECT POB_CODPOL, CODSIS
FROM t
GROUP BY POB_CODPOL, CODSIS;
There's a Bug 28588011 : "ORA-00979: NOT A GROUP BY EXPRESSION" WHEN TABLE FORMAT IS BINARY XML.
Severity 2 - Severe Loss of Service
Created 02-Sep-2018
Status 11 - Code/Hardware Bug (Response/Resolution)
WORKAROUND No
I guess they won't fix it. But the hint NO_XML_QUERY_REWRITE (that I use for other XML related bugs, too) worked for me.
I have a table something like this:
ID|Value
01|1
02|4
03|12
01|5
02|14
03|22
01|9
02|32
02|62
01|13
03|92
I want to know how much progress have each id made (from initial or minimal value)
so in sybase I can type:
select ID, (value-min(value)) from table group by id;
ID|Value
01|0
01|4
01|8
01|12
02|0
02|10
02|28
02|58
03|0
03|10
03|80
But monetdb does not support this (I am not sure may be cz it uses SQL'99).
Group by only gives one column or may be average of other values but not the desired result.
Are there any alternative to group by in monetdb?
You can achieve this with a self join. The idea is that you build a subselect that gives you the minimum value for each id, and then join that to the original table by id.
SELECT a.id, a.value-b.min_value
FROM "table" a INNER JOIN
(SELECT id, MIN(value) AS min_value FROM "table" GROUP BY id) AS b
ON a.id = b.id;