SQL - How to make exclude condition - sql

Question

I have the following table. I'm trying to get the rows that met my specific condition.
Table look as follows:
account|transactiontypecode|
-------|-------------------|
1000058| 8|
1000067| 2|
1000067| 8|
The query output would retrieve only the account 1000058, as it applies to the transactiontypecode 8. The other account applies too, but it also has another transactiontypecode that does not applies.
So requirement would be to get the accounts that meet specifics transaction codes, and excludes accounts even though it can also have the code required but has codes unwanted too.
This was my guess over above issue, among others, but I think that other eyes may guide me on a better direction.
with cte1 as (
select
gp.account,
case
when gp.transactiontypecode in (2,8,17) then TRUE
else false
end as txcheck
from
gp.t2001 gp
group by
1, 2)
select
account,
txcheck
from
cte1
where
txcheck is true and txcheck is not false;
If anyone can help me achieve above requirement, would be great!

Answer 1

Just use not exists if you want the entire rows:
select t.*
from gp.t2001 t
where t.transactiontypecode = 8 and
not exists (select 1
from gp.t2001 t2
where t2.account = t.account and
t2.transactiontypecode <> 8
);
Or aggregation if you just want the account:
select t.account
from gp.t2001 t
group by t.account
having min(transactiontypecode) = max(transactiontypecode) and
min(transactiontypecode) = 8;

Answer 2

You can use aggregation in a HAVING clause checking the count of codes to be exactly one and the code is 8 -- wrap it in e.g. max(), if there's only one value the maximum is that one value:
SELECT gp.account
FROM gp.t2001 gp
GROUP BY gp.account
HAVING count(gp.transactiontypecode) = 1
AND max(gp.transactiontypecode) = 8;
Or, if it is allowed that the code of 8 can occur multiple times for an account and you want all of them not having any other code, change it using conditional aggregation to count the codes of 8 and compare it to the overall count of codes. If they match they're all 8:
...
HAVING count(CASE
WHEN gp.transactiontypecode = 8 THEN
1
END) = count(*);
Another option, if the code may occur more than once is to use NOT EXISTS to check for other rows with another code:
SELECT DISTINCT
gp1.account
FROM gp.t2001 gp1
WHERE gp1.transactiontypecode = 8
AND NOT EXISTS (SELECT *
FROM gp.t2001 gp2
WHERE gp2.account = gp1.account
AND gp2.transactiontypecode <> 8);

Answer 3

Try something like this:
SELECT account
FROM [Table]
GROUP BY account
HAVING
COUNT(transactiontypecode) = 1 AND
transactiontypecode = 8
The COUNT inside having clause should give you the accounts with only 1 transaction type code. Then, you can apply any other condition.