add select query result from tableA as a new column in tableB - mysql

Question

I am creating a new table from joining two tables through below query:
select a.name, a.number, b.id, b.sub_num
from tableA a left join
tableB b
on a.number = concat(id,'-',Cast(sub_num as varchar);
Here, I want to add a new column into the new table which is select query result on tableA.
The table data would be something like below:
enter image description here
I am trying to use below query which is not correct as it is giving me multiple rows. I need sum of dext_number for condition dext_id = 17501 and group by of name and number columns.
select a.name, a.number, b.id, b.sub_num,
(select sum(dext_number) from tableA where dext_id = 17501 group by name, number) as newcol
from tableA a left join tableB b
on a.number = concat(id,'-',Cast(sub_num as varchar);
What is the best way to add this column here?

Answer 1

use following query
select a.name, a.number, b.id, b.sub_num, (select sum(dext_number) over(partition by name, number) from tableA
where dext_id = 'xyz' limit 1) as newcol
from tableA a
left join tableB b on a.number = concat(id,'-',Cast(sub_num as varchar);
If you want the exact output of the query image, use the following query
select L.name,L.number,L.dext_id,L.dext_number,
case when L.num > 1 then newcol
else NULL
end as newcol
from
(select *,
count(dext_number) over(partition by name, number) as num,
sum(dext_number) over(partition by name, number) as newcol
from tableA) L left join tableA R on L.dext_id = R.dext_id and L.name= R.name and L.number = R.number and L.dext_number = R.dext_number
And the combination of the first query with tableB will be as follows
select a.name, a.number, b.id, b.sub_num, (select
case when L.num > 1 then newcol
else NULL
end as newcol
from
(select *,
count(dext_number) over(partition by name, number) as num,
sum(dext_number) over(partition by name, number) as newcol
from Test) L left join Test R on L.dext_id = R.dext_id and L.name= R.name and L.number = R.number and L.dext_number = R.dext_number limit 1) as newcol
from tableA a
left join tableB b on a.number = concat(id,'-',Cast(sub_num as varchar);