So i have this task to resolve in Postgresql where for a given number of classIds that the user provides i have to return him the common properties of said classes.
I have three tables to represent the model (one class has multiple properties and one property can be in many classes)
Table classes:
---------------------------
| Id | Name | Description |
---------------------------
Table Properties:
---------------------------
| Id | Name | Description |
---------------------------
And finally table ClassProperties
------------------------
| ClassId | PropertyId |
------------------------
So the users gives me an array with classIds and i have to return him all common properties of all classes (like i said above)
As of now i'm only being able to return every property of all classes with this code:
select p.*
from properties as p
inner join ClassProperties as cp on cp.propertyid= p.id
where cp.classid = any ('{88d5fe8f-e19e-40b4-bc65-83ac64f825b0, a2a63bea-
aeee-4d3b-817e-cc635383c571}') ;
The ids as u can see are Guid, but that really does't matter. Any help would be appreciated. Thanks!
You can do this as:
select p.*
from properties p inner join
ClassProperties cp
on cp.propertyid = p.id
where cp.classid = any ('{88d5fe8f-e19e-40b4-bc65-83ac64f825b0, a2a63bea-aeee-4d3b-817e-cc635383c571}')
group by p.id
having count(*) = 2;
The count(*) should be count(distinct classid) if duplicates are allowed.
Note: the value "2" is the number of elements you are checking. You can also use array_length('{88d5fe8f-e19e-40b4-bc65-83ac64f825b0, a2a63bea-aeee-4d3b-817e-cc635383c571}').
Related
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;
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;
I would like to know an efficient to way to fetch the data in the following case.
There are two tables say Table1 and Table2 having two common field say contry and pincode and other table "Table3" having key fields of first two tables (DNO, MPNO).
Here is the little glitch, In table3 data, if it is having DNO it wont have MPNO
So when in the selection screen(Pic no2) if the use enter any thing, result should be as follows
**MFID | DNO | MPNO | COUNTRY | PINCODE**
----------
00001 | 10011 | novalue | IN | 4444
00002 | Novalue | 1200 | IN | 5555
00003 | 300 | novalue | US | 9999
( as you can observe if DNO present no MPNO , vice versa )
Please have a look at the pictures for a clear picture :-)
Table Relation:
Selection screen with select options:
The code shouldn't be long.
PSEUDO CODE:
Select queries:
Select * from table3 into it_table3.
Select * from table1 FOR ALL ENTRIES IN it_table3 INTO it_table1
WHERE dno = table3-dno.
Select * from table2 FOR ALL ENTRIES IN it_table3 INTO it_table2
WHERE mpno = table3-mpno.
Loop at internal table 3 and build final table.
LOOP at it_table3 into wa_table3.
IF wa_table3-dno IS NOT INITIAL.
READ it_table1 where dno = wa_table3-dno.
ELSE.
READ it_table2 where mpno = wa_table3-mpno.
ENDIF.
ENDLOOP.
Hope this was the answer you were hoping to find!
Building of efficient select will require information about obligatory fields in your selection screen, as well as about alleged production size of all 3 tables. However, without this information let's assume that table1 and table2 are reference tables and table3 is a transaction table, as onr can assume from their structure. It would be sensible to build selection in a following way:
Selecting data from reference tables. As you said fields DNO/MPNO are mutually exclusive then there will be no hits of country/pincode pair in both reference tables, so JOIN is useless here. However we can merge 2 result sets in single itab without any constraints' violations.
TYPES: BEGIN OF tt_result,
dno TYPE table1-dno,
mpno TYPE table2-mpno,
country TYPE table1-country,
pincode TYPE table1-pincode,
...other field from table3
END OF tt_result.
DATA: itab_result TYPE tt_result.
SELECT dno
FROM table1
INTO CORRESPONDING FIELDS OF TABLE itab_result
WHERE pincode IN so_pincode
AND country IN so_country.
SELECT mpno
FROM table2
APPENDING CORRESPONDING FIELDS OF TABLE itab_result
WHERE pincode IN so_pincode
AND country IN so_country.
FOR ALL ENTRIES addition allows specifying the same table in FOR ALL ENTRIES clause and in INTO clause, so we can fill our result table with absent table3 data by DNO/MPNO key.
SELECT *
FROM table3
INTO CORRESPONDING FIELDS OF TABLE itab_result
FOR ALL ENTRIES IN itab_result
ON itab_result~dno = itab3~dno
AND itab_result_mpno = itab3~mpno.
Sorry if title isn't very descriptive. I have a table like this example, and am using sql server 2012:
PersonId | PetID
and want to join it to the following two tables
PersonId | PersonName | PersonAsset
AnimalId | AnimalName | Animal Asset
So the end result is:
PersonId | PetId | Name | Asset
-------------------------------
1 null Dave 1
null 1 Fido 2
The output you require can be achieved by using a LEFT JOIN for your two tables and ISNULL for the required fields.
For example (assuming the first table is named 'common'):
SELECT common.PersonId,
common.PetId,
ISNULL(person.PersonName, animal.AnimalName) AS Name,
ISNULL(person.PersonAsset, animal.AnimalAsset) AS Asset
FROM common
LEFT JOIN person ON common.PersonId = person.PersonId
LEFT JOIN animal ON common.AnimalId = animal.AnimalId