Re: determining time difference between two timestamp fields.

yea, not sure why my Query isn't returning a value though? If I don't use date(), what should I use? the SQL for the timestamps looks like this. login_timestamp datetime NOT NULL default '0000-00-00 00:00:00', submit_timestamp timestamp NOT NULL default CURRENT_TIMESTAMP, sorry for the top-posting, but I think you have to in gmail. On Tue, May 25, 2010 at 3:14 PM, Peter Lind <peter.e.lind@gmail.com> wrote: > On 25 May 2010 21:09, Bruce Gilbert <webguync@gmail.com> wrote: >> the resulting output with that code is a little weird. I get September >> 3, 1970 2:39:32pm >> >> I think part of the problem is my Query. When I run it in PHP MyAdmin >> I get a null value for login_timestamp even though there is indeed a >> timestamp there. The Query again is: >> >> SELECT >> Responses.editor_name,Answer1,Answer2,Answer3,Answer4,Answer5,Answer6,Answer7,Answer8,Answer9,Answer10,Answer11,Answer12,submit_timestamp,login_timestamp >>        FROM Responses LEFT JOIN Candidates USING (user_id) >> >> login_timestamp is in a table called 'Candidates' and submit_timestamp >> is in a tables called 'Responses'. >> >> thanks for all the help to this point. >> >> On Tue, May 25, 2010 at 2:28 PM, Ashley Sheridan >> <ash@ashleysheridan.co.uk> wrote: >>> On Tue, 2010-05-25 at 14:22 -0400, Bruce Gilbert wrote: >>>> echo "<tr><th>Completion >>>> Time:</th></tr><tr><td>". date('F j, Y >>>> g:i:sa',strtotime($row['submit_timestamp']) - >>>> strtotime($row['login_timestamp']))/60 , >>>> "</td></tr>"; >>> >>> There's a good reason for that! What you're actually doing is this: >>> >>> echo "<tr><th>Completion >>> Time:</th></tr><tr><td>" . >>>  date('F j, Y g:i:sa', >>>    strtotime($row['submit_timestamp']) - >>>    strtotime($row['login_timestamp']) >>>  ) >>>  / 60 >>>  , "</td></tr>"; >>> >>> You're trying to divide a string by 60, because date() returns a string.. >>> Put that division inside the brackets for date() rather than outside. >>> >>> It might help to break up that whole line of output into several parts. >>> Put the date into a variable and then just output the HTML line: >>> >>> $date = date('F j, Y g:i:sa', (strtotime($row['submit_timestamp']) >>> - >>> strtotime($row['login_timestamp']))/60); >>> echo "<tr><th>Completion >>> Time:</th></tr><tr><td>$date</td></tr>"; >>> > > There are two problems you're looking at. The first is the null value > you're getting, which will invalidate the whole thing. The second > problem is that you were looking for output along the lines of "60 > minutes" but you're using date() which as the second parameter expects > a unix timestamp - not two timestamps subtracted from each other. >  On another note, subtracting the output of two strtotime() calls > inside the date() call doesn't amount to subtracting anything from a > string. > > Regards > Peter > > -- > <hype> > WWW: http://plphp.dk / > http://plind.dk > LinkedIn: http://www.linkedin.com/in/plind > BeWelcome/Couchsurfing: Fake51 > Twitter: http://twitter.com/kafe15 > </hype> > -- ::Bruce::