SQL WHERE statement returning both or conditions - sql

Question

I'm trying to return a single row based on this where statement
WHERE
(C.id = G.community_id
AND P.service_type_id = G.service_type_id
AND I.unit_class_id = G.unit_class_id)
OR
(C.id = G.community_id
AND P.service_type_id = G.service_type_id)
The issue is I have to get a row based on multiple criteria and the more that match determines the final match. The statement above returns a row just fine if it matches the bottom or statement, but if it matches the first OR it returns results for both statements.
LIMIT 1 doesn't work either as sometimes it gives preference to the wrong result.
EDIT:
community_id
service_type_id
unit_class_id
1
1
1
1
1
null
Because of the way the table is both rows are true, my understanding was SQL took the first one that was true and returned it.
I apologize for not a lot of info I was hoping maybe there was just a bit of info I was missing. Here is my query.
CREATE VIEW view_invoice_line_item_gl_code
AS
SELECT
DISTINCT(ILI.invoice_line_item_id) AS invoice_line_item_id,
C.community_id AS community_id,
S.service_type_id AS service_type_id,
U.unit_class_id AS unit_class_id,
LIP.line_item_provider_id AS line_item_provider_id,
(SELECT gl_code_id
FROM gl_code G
WHERE (C.community_id = G.community_id
AND P.service_type_id = G.service_type_id)
AND ((G.unit_class_id IS NULL
AND G.line_item_provider_id IS NULL)
OR
(I.unit_class_id = G.unit_class_id
AND G.line_item_provider_id IS NULL)
OR
(I.unit_class_id = G.unit_class_id
AND ILI.line_item_provider_id = G.line_item_provider_id)
)) AS gl_code_id
FROM
invoice I
JOIN
invoice_line_item ILI ON (ILI.invoice_id = I.invoice_id)
JOIN
invoice_header IH ON (I.invoice_header_id = IH.invoice_header_id)
JOIN
provider_community_account PC ON (I.provider_community_account_id = PC.provider_community_account_id)
JOIN
line_item_provider LIP ON (ILI.line_item_provider_id = LIP.line_item_provider_id)
JOIN
unit_class U ON (I.unit_class_id = U.unit_class_id)
JOIN
community C ON (PC.community_id = C.community_id)
JOIN
provider P ON (PC.provider_id = P.provider_id)
JOIN
service_type S ON (P.service_type_id = S.service_type_id)

Answer 1

I'm assuming that you want to get the record that matches the most conditions first. One way to do that is to order by the number of matching conditions (in this case only one condition is different):
SELECT TOP 1 ...
FROM ...
WHERE
C.id = G.community_id
AND P.service_type_id = G.service_type_id
ORDER BY CASE WHEN I.unit_class_id = G.unit_class_id THEN 1 ELSE 0 END DESC

Answer 2

The first condition implies the second, so you can simplify it like this:
WHERE
C.id = G.community_id
AND P.service_type_id = G.service_type_id
You say where (A AND B) OR A so where A is sufficient.

Answer 3

You'll need to compute a "score" somehow. If you consider each predicate awards 1 point, then you could do something like:
select *
from (
select *,
case when <predicate1> then 1 else 0 end +
case when <predicate2> then 1 else 0 end as score
from t
WHERE
(C.id = G.community_id
AND P.service_type_id = G.service_type_id
AND I.unit_class_id = G.unit_class_id
)
OR
(
C.id = G.community_id
AND P.service_type_id = G.service_type_id
)
)
ORDER BY score DESC
LIMIT 1