The ANSI join syntax represents a bit of an adjustment to developers who are used to using Oracle's traditional join syntax, including the outer join operator (+). However, there are several advantages to using the syntax introduced in Oracle9i Database:
The new join syntax follows the ANSI standard, making your code more portable.
The ON and USING clauses keep join conditions away from the filter conditions in the WHERE clause. This enhances development productivity and the maintainability of your code.
The ANSI/ISO syntax makes it possible to perform a full outer join without having to perform a UNION of two SELECT queries.
We recommend that while working with Oracle9i Database and later Oracle releases, you use the new join syntax instead of the traditional join syntax.