In addition to inner, left, right, and full joins, users can request cross joins (effectively inner joins without an ON clause) and natural joins. Also, the ON clause can be replaced by a USING clause that contains a list of columns, each of which appears in both tables being joined. Instead of the explicitly coded join qualification of the ON clause, the USING clause applies one equijoin predicate for each column pair in the list of columns. For example, “… a left join b using c1, c2 …” is identical to coding “… a left join b on a.c1 = b.c1 and a.c2 = b.c2 ….” For more information, see the SQL Reference Guide.