Hi, Fay,
Fay Du wrote:
> Table cost
>
> Id edge_id cost
> 1 30 101.4
> 2 30 null
> 3 40 500.2
> 4 40 null
> 5 45 300.7
> 6 45 null
> I want to set cost value with same edge_id by same value. The existing
> values are calculated by calling a function (calculate edge length). I
> can calculate the value by same function, but the function was slow. I
> wander if I can use update statement to set the second value with same
> edge_id. Thanks in advance for your help.
It should go like:
UPDATE cost SET edge_id = (SELECT cost FROM cost innr WHERE innr.edge_id
= edge_id AND innr.cost is not null) WHERE cost is null;
HTH,
Marku
--
Markus Schaber | Logical Tracking&Tracing International AG
Dipl. Inf. | Software Development GIS
Fight against software patents in EU! www.ffii.org www.nosoftwarepatents.org
