Update inner join result Oracle - sql

Question

In my java code I have foreach loop which iterates though list
foreach(MyObject obj:list){
String status = obj.getStatus();
String is = obj.getId();
// DB call
1. To update Status in Table A
jdbcobj.updtastatus(status,id);
2. Get status from table B
String tableBStatu= jdbcobj.getstatufromtableB(status,id):
obj.setStatus(tableBStatus):
}
To avoid 2 dB calls in for loop I am using inner join and trying to achieve same output as above
I am using inner-join and get the new result set based on common field.I want to update the result set but I am unable to figure out how?
I have two tables "A" and "B".
Table "A" has columns id,name,statusA
Table "B" has columns id,city,statusB
As stated at start, I am using inner-join and my query looks like this.
Select A.id A.statusA,B.statusB FROM A INNER JOIN ON B where A.id=B.id
Which gives me result as "id", status from table "A" and status from table "B".
Now i want use the inner-join result, to update statusA column from table "A" and set value ="DONE"
And want to use the statusB column value in java object.
String statusfromColumnB = get statusB col value
and set in my java object like this
myObj.setStatus(statusfromColumnB)
Sample Data
Suggest a solution.

Answer 1

If I understand you correctly, an Oracle MERGE query could properly respond to your need :
Consider :
MERGE INTO A
USING B ON (A.id = B.id)
WHEN MATCHED THEN UPDATE SET A.statusA = B.statusB
This query will update the status in table A from that of the corresponding record in table B.
Oracle merge is a vendor-specific statement that is optimized for multi-rows upserts (inserts/updates).
Demo on DB Fiddle :
Select A.id, A.statusA, B.statusB FROM A INNER JOIN B ON A.id=B.id
ID | STATUSA | STATUSB
-: | :------ | :--------
1 | Pending | Initiated
2 | Pending | Completed
MERGE INTO A
USING B ON (A.id = B.id)
WHEN MATCHED THEN UPDATE SET A.statusA = B.statusB
2 rows affected
Select A.id, A.statusA, B.statusB FROM A INNER JOIN B ON A.id=B.id
ID | STATUSA | STATUSB
-: | :-------- | :--------
1 | Initiated | Initiated
2 | Completed | Completed
If you want to set statusA to a fixed value instead, then you could go :
MERGE INTO A
USING B ON (A.id = B.id)
WHEN MATCHED THEN UPDATE SET A.statusA = 'Finished'

Answer 2

Do you want something like this?
update a
set (status, somewhereelsecolumn) =
(select 'DONE', <whatever>
from b
where A.id = B.id
)
where exists (select 1 from b where a.id = b.id);