Path: text.usenetserver.com!out03a.usenetserver.com!news.usenetserver.com!in02.usenetserver.com!news.usenetserver.com!postnews.google.com!f40g2000pri.googlegroups.com!not-for-mail From: jeremy Newsgroups: comp.databases.oracle.server Subject: Looking for "gaps" (from a time perspective) in data Date: Fri, 10 Oct 2008 02:53:14 -0700 (PDT) Organization: http://groups.google.com Lines: 27 Message-ID: NNTP-Posting-Host: 193.164.109.10 Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Trace: posting.google.com 1223632394 17100 127.0.0.1 (10 Oct 2008 09:53:14 GMT) X-Complaints-To: groups-abuse@google.com NNTP-Posting-Date: Fri, 10 Oct 2008 09:53:14 +0000 (UTC) Complaints-To: groups-abuse@google.com Injection-Info: f40g2000pri.googlegroups.com; posting-host=193.164.109.10; posting-account=h5IA6woAAABcHbb4vAIZFk2TfZkZ_eqe User-Agent: G2/1.0 X-HTTP-UserAgent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-GB; rv:1.9.0.3) Gecko/2008092417 Firefox/3.0.3,gzip(gfe),gzip(gfe) Xref: usenetserver.com comp.databases.oracle.server:448554 X-Received-Date: Fri, 10 Oct 2008 05:53:14 EDT (text.usenetserver.com) This is on 10gR2 standard edition. We have a table defined like this: txn_id date_start date_end url_called which contains a record for every time our application processes a request from a browser. We would like to be able to spot any "gaps" in the data - which would indicate a period when the service was unavailable for whatever reason. To do this we need to do a comparison between the date_start of each row and the one that preceded (or followed) it and then see if the period of time is greater than a to-be-determined threshold. Can a single SQL statement be constructed which could achieve this? if so could you point me in the right direction? For those who haven't followed what I was asking about, if you are in the majority then please accept my apologies for not being more concise :) regards, -- jeremy