Sql join only 1 row - sql

Question

I want to join the table CustomerAgreementRole with only one row from AgreementRoleGroup, based on ViewPriority. Example: CustomerAgreementRole can have three rows. I only want the joined row where ViewPriority is highest
AgreementId, AgreementRoleId
1 1
1 2
1 3
CustomerAgreementRole
1. AgreementId
2. AgreementRoleId
AgreementRoleGroup
1. AgreementRoleId
2. ViewPriority
Current query:
select * from CustomerAgreementRole car
join (select agreementRoleId, min(ViewPriority) as mi from AgreementRoleGroup group by AgreementRoleId) as arg on car.AgreementRoleId = arg.AgreementRoleId
Expected result:
AgreementId, AgreementRoleId, ViewPriority
1 1 1

Answer 1

May be something like this:
SELECT *
FROM CustomerAgreementRole A
CROSS APPLY
(
SELECT TOP 1 *
FROM AgreementRoleGroup B
WHERE A.[AgreementRoleId] = B.[AgreementRoleId]
ORDER BY ViewPriority DESC
) C

Answer 2

Since AgreementRoleGroup already got AgreementRoleId we can just join with some subquery
select a.*, b2.ViewPriority from CustomerAgreementRole a left join
(
select b.AgreementRoleId, b.ViewPriority
from AgreementRoleGroup b
where b.ViewPriority =
(
select min(ViewPriority)
from AgreementRoleGroup
)
) b2
on a.AgreementRoleId=b2.AgreementRoleId
But I'll say that using min() isn't the best way,you should use top in #gotqn answer but right now this will work.
re-edit
create table CustomerAgreementRole (AgreementId int,AgreementRoleId int);
insert into CustomerAgreementRole values (1,1);
insert into CustomerAgreementRole values (2,3);
insert into CustomerAgreementRole values (3,4);
insert into CustomerAgreementRole values (4,2);
create table AgreementRoleGroup (AgreementRoleId int, ViewPriority int);
insert into AgreementRoleGroup values (1,3);
insert into AgreementRoleGroup values (3,4);
insert into AgreementRoleGroup values (4,2);
insert into AgreementRoleGroup values (2,1);
I use those as sample data and got this result db<>fiddle
if you just want that one row and don't care ViewPriority need to be min, use top instead
select top 1 a.*, b.ViewPriority from CustomerAgreementRole a left join
AgreementRoleGroup b
on a.AgreementRoleId=b.AgreementRoleId
order by ViewPriority asc

Answer 3

Per AgreementId you want the AgreementRoleId with the highest priority (lowest ViewPriority value). This means you want to rank the CustomerAgreementRole rows and only show the best ranked ones. Ranking is typically done with ROW_NUMBER, RANK or DENSE_RANK in SQL.
select AgreementId, AgreementRoleId, ViewPriority
from
(
select
car.AgreementId, car.AgreementRoleId, arg.ViewPriority,
row_number() over (partition by car.AgreementId order by arg.ViewPriority) as rn
from CustomerAgreementRole car
join AgreementRoleGroup arg on arg.AgreementRoleId = car.AgreementRoleId
) ranked
where rn = 1;

Answer 4

Made it working with this:
WITH CTEViewPriority (lowestViewPriority, agreementId) as (
select min(ViewPriority), AgreementId from CustomerAgreementRole as car
left join AgreementRoleGroup arg on car.AgreementRoleId = arg.AgreementRoleId
group by agreementId
)
select * from CustomerAgreementRole as car
inner join CTEViewPriority as arg on lowestViewPriority = arg.agreementRoleId and arg.agreementId = car.agreementId