SQL & PL/SQL

Which is more efficient?

An IMPLICIT JOIN

SELECT TableA.ColumnA1,
TableB.ColumnB2
FROM TableA,
TableB
WHERE TableA.ColumnA1 = TableB.ColumnB1

Or....An EXPLICIT JOIN

SELECT TableA.ColumnA1,
TableB.ColumnB2
FROM TableA
INNER JOIN TableB
ON TableA.ColumnA1 = TableB.ColumnB1

I have to write a pretty extensive query and there will be many parts and I just want to try and make sure it is efficient as possible. Can I EXPLAIN this in SQL Navigator as well to find out???

Thanks in advance for your review and hopeful for a reply.

PSULionRP