How to select data with a complex condition? - sql

Question

Using Microsoft Access, I normally use condition (mostly where) to obtain the data I want to display.
So far, it went well. However now I have a complex filtering and I'm not sure of the best way to do it. I will explain how I do it with many queries, and I'd like to know if there is something simpler, since I feel like it's doing too much for what I accomplish.
I have Building and Energy tables. Between them, I have a link table since a Building has a list of possible energies.
My goal is to display ALL energy not already associated with the building.
I first have a simple query to display all the IDs of energy that are in the link table where building is the one of interest.
Once I do that, I have another query using this one, which display an energy if it is an energy absent from previous list.
This takes 2 queries and I feel like I could have a better way to do this. I'm fairly new to MS Access, so any suggestion is welcome.
Here is the first request to obtain the list of energies:
SELECT
Batiments.ID, Energies.ID, Energies.Type
FROM
Energies
INNER JOIN
(Batiments
INNER JOIN
Batiment_Energie ON Batiments.ID = Batiment_Energie.Batiment_ID) ON Energies.ID = Batiment_Energie.Energie_ID
WHERE
(((Batiments.ID) = " & cbxBatiments.Column(0) & "));"

Answer 1

You can query the non-associated energy types with
SELECT
ID, Type
FROM
Energies
WHERE
ID NOT IN (SELECT Energie_ID
FROM Batiment_Energie
WHERE Batiment_ID = 123)
where 123 is to be replaced by the Id comming from cbxBatiments.Column(0).

Answer 2

You can use not exists:
select e.*
from energie as e
where not exists (select 1
from Batiment_Energie as be
where be.energie_id = e.id and be.batiment_id = <your id>
);