SQL JOIN - WHERE clause vs. ON clause

Question

After reading it, this is not a duplicate of Explicit vs Implicit SQL Joins. The answer may be related (or even the same) but the question is diffe

Answer 1

For an inner join, WHERE and ON can be used interchangeably. In fact, it's possible to use ON in a correlated subquery. For example:

update mytable
set myscore=100
where exists (
select 1 from table1
inner join table2
on (table2.key = mytable.key)
inner join table3
on (table3.key = table2.key and table3.key = table1.key)
...
)

This is (IMHO) utterly confusing to a human, and it's very easy to forget to link table1 to anything (because the "driver" table doesn't have an "on" clause), but it's legal.