Robert James <srobertjames@xxxxxxxxx> writes: >> (To elaborate, I'm interested in: >> * Finding field x of the _previous_ row >> * Finding field x of the _next_ row >> * Finding field x of the _previous_ row that meets a certain criteria >> (which the current row may or may not meet) >> ) > The first two are actually trivial - lag(field_x) over (order by [same > order as query]) and lead(...). Right. > But the last one seems ellusive - How can I find the value of field x > on the previous row WHERE a criteria is met? Is it possible to do this > at all with a window function? I don't see any way to achieve that with any of the built-in window functions, but I believe it could be done by a custom window function. Are you up for some C coding? regards, tom lane -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
