count specific data changes in adjacent ordered rows

From: cate <catebekensail_at_yahoo.com>
Date: Fri, 11 Dec 2009 17:04:57 -0800 (PST)
Message-ID: <9190f9b2-64b9-47c5-84c9-aa30468d3ff0_at_p35g2000yqh.googlegroups.com>

a b c time
a b d time
a b e time
a b c time
a b x time
a b d time

I want to count all the c -> x transitions found in adjacent rows. The table is ordered. The count is one in the above example. Oracle SQL

Thank you. Received on Fri Dec 11 2009 - 19:04:57 CST