[fdo-users] Conditional "IF" in Expressions

[Orest Halustchak]

Hi Maksim,

This seems doable. It's similar to a null value function that some
providers such as rdbms providers could support: nvl(a,b) which returns
a if a is not null, otherwise b. In your case it's if(a,b,c) where a is
boolean. This would need a number of signatures for different data types
that it would return, e.g. int16 = if(boolean, int16, int16), but
FdoFunctionDefinition can deal with it.

The main concern that I would have about it is implementation in an
efficient manner, although for rdbms providers, SQL includes a CASE
expression that could be used.

Thanks,
Orest.

-----Original Message-----
From: fdo-users-bounces at lists.osgeo.org
[mailto:fdo-users-bounces at lists.osgeo.org] On Behalf Of Maksim Sestic
Sent: Wednesday, July 18, 2007 4:52 AM
To: fdo-users at lists.osgeo.org
Subject: [fdo-users] Conditional "IF" in Expressions


I was wondering if future versions of FDO will support conditional
branching
in Expressions (and Filtering) mechanism, i.e.:

if(conditional_expression,true_part,false_part)

if(Road.Lanes>1,"Multiple lanes","Single lane")

also

if(Road.Lanes>0,if(Road.Lanes>1,"Multiple lanes","Single lane"),"No
lanes
set")

Useful link:
http://www.codeplex.com/dotMath Steve Heberts dotMath library 

Regards,
Maksim Sestic


-- 
View this message in context:
http://www.nabble.com/Conditional-%22IF%22-in-Expressions-tf4101935s1816
2.html#a11664863
Sent from the fdo-users mailing list archive at Nabble.com.

_______________________________________________
fdo-users mailing list
fdo-users at lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/fdo-users