http://sqlfiddle.com/#!15/157ad/3
Is it possible to group by on multiple columns and then put the results on that aggregate in to a table.
I am trying to ask the database to tell me to find all the shipments and for each shipment what are the containers belonging to that shipment and what are the locations each shipment goes to. I am able to do this for one grouping, but I can't figure out for two group by clauses. Is it possible to ask this question in one single sql query?
select
s.shipmentName,
array_agg(distinct sc.pk_shipmentContainerId) as container,
array_agg(distinct l.locationName) as location
from
shipment s
inner join
shipmentContainer sc on s.pk_shipmentId = sc.fk_shipmentId
inner join
shipmentMove sm on s.pk_shipmentId = sm.fk_shipmentId
inner join
location l on sm.fk_locationId = l.pk_locationId
group by s.pk_shipmentId, 1
order by s.pk_shipmentId
;
shipmentname | container | location
-------------------------------------+---------------+-------------------------------------------------------
1.shipment of bananas - Loc 1,2,3,4 | {1,2,3} | {"Location 1","Location 2","Location 3","Location 4"}
2.shipment of apples Loc 1,2,3,4 | {4} | {"Location 1","Location 2","Location 3","Location 4"}
3.more bananas Loc 1,2,4,5 | {5,6,7,8,9} | {"Location 1","Location 2","Location 4","Location 5"}
5.lots of pants Loc 5,3,2,1 | {10,11,12,13} | {"Location 1","Location 2","Location 3","Location 5"}
Related
This is db query .
select users.Id,jsonb_object_keys(orders.metadata::jsonb) from users left join orders on users.userId=orders.userId where users.userId=2;
users table orders table
------------------- -----------------------------------------------------
|userId| name | | userId|orderId|metadata |
| 1 | john | | 1 | 1 | {"orderName":"chess","quantity":1}|
| 2 | doe | | 1 | 2 | {"orderName":"cube" ,"quantity":1}|
------------------- -----------------------------------------------------
Why there are no rows returned by the query ?
Very Nice and tricky question. to achieve what you want you should try below query:
select
t1.userid,
t2.keys
from
users t1
left join (select userid, orderid, jsonb_object_keys(metadata) as keys from orders) t2
on t1.userid=t2.userid
Your Query seems correct but there is catch. When you are left joining both tables without jsonb_object_keys(metadata), it will work as you are expecting. But when you use with this function then this function will return a set of records for each rows of select statement and perform simple join with rest of the columns internally. That's why it will remove the rows having NULL value in second column.
You should left join to the result of the jsonb_each() call:
select users.userid, meta.*
from users
left join orders on users.userid = orders.userid
left join jsonb_object_keys(orders.metadata::jsonb) as meta on true
where users.userid = 2;
I would like to ask your help to create a postgresql query so that I can left join categories & products tables and replace the prodcutnums with the actual product names.
Below you can see the tables structures & desired output for the query
Categories Table:
name | productnums
---------------------------------+------------------------------
Books | {605,614,663,647,645,619,627}
Kitchen | {345,328}
Electronics | {145,146}
Products Table:
id | name
---------------------------------+----------------------
145 | LCD Monitor
147 | Mouse
345 | Glass
Desired Output:
name | productnums
---------------------------------+-------------------------------------------
Electronics | {LCD Monitor,Mouse}
I will appreciate any kind of support.
You can use the ANY operator in a JOIN condition, then use array_agg to aggregate the product names.
select c.name,
array_agg(p.name) as products
from categories c
left join products p on p.id = any(c.productnums)
group by c.name;
Four categories in category table.
id | name
--------------
1 | 'wine'
2 | 'chocolate'
3 | 'autos'
4 | 'real estate'
Two of the many (thousands of) forecasters in forecaster table.
id | name
--------------
1 | 'sothebys'
2 | 'cramer'
Relevant forecasts by the forecasters for the categories in the forecast table.
| id | forecaster_id | category_id | forecast |
|----+---------------+-------------+--------------------------------------------------------------|
| 1 | 1 | 1 | 'bad weather, prices rise short-term' |
| 2 | 1 | 2 | 'cocoa bean surplus, prices drop' |
| 3 | 1 | 3 | 'we dont deal with autos - no idea' |
| 4 | 2 | 2 | 'sell, sell, sell' |
| 5 | 2 | 3 | 'demand for cocoa will skyrocket - prices up - buy, buy buy' |
I want prioritized mapping of (forecaster, category, forecast) such that, if a forecast exists for some primary forecaster (e.g. 'cramer') use it because I trust him more. If a forecast exists for some secondary forecaster (e.g. 'sothebys') use that. If no forecast exists for a category, return a row with that category and null for forecast.
I have something that almost works and after I get the logic down I hope to turn into parameterized query.
select
case when F1.category is not null
then (F1.forecaster, F1.category, F1.forecast)
when F2.category is not null
then (F2.forecaster, F2.category, F2.forecast)
else (null, C.category, null)
end
from
(
select
FR.name as forecaster,
C.id as cid,
C.category as category,
F.forecast
from
forecast F
inner join forecaster FR on (F.forecaster_id = FR.id)
inner join category C on (C.id = F.category_id)
where FR.name = 'cramer'
) F1
right join (
select
FR.name as forecaster,
C.id as cid,
C.category as category,
F.forecast
from
forecast F
inner join forecaster FR on (F.forecaster_id = FR.id)
inner join category C on (C.id = F.category_id)
where FR.name = 'sothebys'
) F2 on (F1.cid = F2.cid)
full outer join category C on (C.id = F2.cid);
This gives:
'(sothebys,wine,"bad weather, prices rise short-term")'
'(cramer,chocolate,"sell, sell, sell")'
'(cramer,autos,"demand for cocoa will skyrocket - prices up - buy, buy buy")'
'(,"real estate",)'
While that is the desired data it is a record of one column instead of three. The case was the only way I could find to achieve the ordering of cramer first sothebys next and there is lots of duplication. Is there a better way and how can the tuple like results be pulled back apart into columns?
Any suggestions, especially related to removal of duplication or general simplification appreciated.
This sounds like a case for DISTINCT ON (untested):
SELECT DISTINCT ON (c.id)
fr.name AS forecaster,
c.name AS category,
f.forecast
FROM forecast f
JOIN forecaster fr ON f.forecaster_id = fr.id
RIGHT JOIN category c ON f.category_id = c.id
ORDER BY
c.id,
CASE WHEN fr.name = 'cramer' THEN 0
WHEN fr.name = 'sothebys' THEN 1
ELSE 2
END;
For each category, the first row in the ordering will be picked. Since Cramer has a higher id than Sotheby's, it will be given preference.
Adapt the ORDER BY clause if you need a more complicated ranking.
Let's say I have this 3 tables
Countries ProvOrStates MajorCities
-----+------------- -----+----------- -----+-------------
Id | CountryName Id | CId | Name Id | POSId | Name
-----+------------- -----+----------- -----+-------------
1 | USA 1 | 1 | NY 1 | 1 | NYC
How do you get something like
---------------------------------------------
CountryName | ProvinceOrState | MajorCities
| (Count) | (Count)
---------------------------------------------
USA | 50 | 200
---------------------------------------------
Canada | 10 | 57
So far, the way I see it:
Run the first SELECT COUNT (GROUP BY Countries.Id) on Countries JOIN ProvOrStates,
store the result in a table variable,
Run the second SELECT COUNT (GROUP BY Countries.Id) on ProvOrStates JOIN MajorCities,
Update the table variable based on the Countries.Id
Join the table variable with Countries table ON Countries.Id = Id of the table variable.
Is there a possibility to run just one query instead of multiple intermediary queries? I don't know if it's even feasible as I've tried with no luck.
Thanks for helping
Use sub query or derived tables and views
Basically If You You Have 3 Tables
select * from [TableOne] as T1
join
(
select T2.Column, T3.Column
from [TableTwo] as T2
join [TableThree] as T3
on T2.CondtionColumn = T3.CondtionColumn
) AS DerivedTable
on T1.DepName = DerivedTable.DepName
And when you are 100% percent sure it's working you can create a view that contains your three tables join and call it when ever you want
PS: in case of any identical column names or when you get this message
"The column 'ColumnName' was specified multiple times for 'Table'. "
You can use alias to solve this problem
This answer comes from #lotzInSpace.
SELECT ct.[CountryName], COUNT(DISTINCT p.[Id]), COUNT(DISTINCT c.[Id])
FROM dbo.[Countries] ct
LEFT JOIN dbo.[Provinces] p
ON ct.[Id] = p.[CountryId]
LEFT JOIN dbo.[Cities] c
ON p.[Id] = c.[ProvinceId]
GROUP BY ct.[CountryName]
It's working. I'm using LEFT JOIN instead of INNER JOIN because, if a country doesn't have provinces, or a province doesn't have cities, then that country or province doesn't display.
Thanks again #lotzInSpace.
So, I've got two tables - PLUTO (pieces of land), and NYZMA (rezoning boundaries). They look like:
pluto nyzma
id | geom name | geom
-------------------- -------------------
1 | MULTIPOLYGON(x) A | MULTIPOLYGON(a)
2 | MULTIPOLYGON(y) B | MULTIPOLYGON(b)
And I want it to spit out something like this, assuming that PLUTO record 1 is in multipolygons A and B, and PLUTO record 2 is in neither:
pluto_id | nyzma_id
-------------------
1 | [A, B]
2 |
How do I, for every PLUTO record's corresponding geometry, cycle through each NYZMA record, and print the names of any whose geometry matches?
Join the two tables using the spatial function ST_Contains. Than use GROUP BY and ARRAY_AGG in the main query:
WITH subquery AS (
SELECT pluto.id, nyzma.name
FROM pluto LEFT OUTER JOIN nyzma
ON ST_Contains(nyzma.geom, pluto.geom)
)
SELECT id, array_agg(name) FROM subquery GROUP BY id;