Oracle – update data in first table with rows from second table

How to update ‘date_from’ (t1) using ‘modfied’ (t2) when it is like 20/07/20.

So in this case in t1 id’s 1 and 2 are to be updated and id 3 stays.

Table 1:

id    date_from
-----------------------
1     13/07/30
2     13/07/30
3     13/07/30

Table 2:

id    name    modified
-----------------------
1     x       20/07/20
2     y       20/07/20
3     z       19/05/10

Answer

You know in advance which value needs to be assigned, so you just need to filter which rows should be updated. exists seems sufficient:

update t1 
set date_from = date '2020-07-20'
where exists (
    select 1 from t2 where t2.id = t1.id and t2.modified = date '2020-07-20'
)