T1 - table one with only one column
Bart
Philip
Beth
T2 - table two with only one column
Robert
Bart
Philip
Ann
Jack
Helen
Beth
The expected result after JOIN is:
Robert
Ann
Jack
Helen
What you are after is a simple outer join
select t2.col
from t2
left join t1 on t2.col=t1.col
where t1.col is null
You can also express it as a not exists
select *
from t2
where not exists(select 1 from t1 where t2.col=t1.col)
You can also express it using except
select *
from t2
except
select *
from t1