how to avoid nested if

[#1]

I have an expression that is essentially:

if exp1 is not null then

exp1

else

exp2;

if exp2 is not null then

exp2

else

exp3;

etc...

if expn is not null then

expn

else

'Unknown';

I can't do this in the load statement because each of these expressions are based off of user input.  Essentially, I have a hierarchy classifications.  A record could have a value for several different sources of classifications and the user can change their hierarchy (preferred order of classifications) for all securities.  Some securities may only have classifications from a classification source that the user does not select, which is the reason for the 'Unknown' at the end of the nested if.  I'm hoping there is a better way to do this process in QV as it will be pervasive across many reports and I expect would hit performance.  Any suggestions would be greatly appreciated.

[marcus_sommer]

You could try it with the function alt().

- Marcus

[ThornOfCrowns]

This: http://community.qlik.com/docs/DOC-5841 might help, hopefully.

[#4]

That link says at the end that the speed compared to a nested if was not any different.  Is my assumption that nested ifs are big hits to performance?

[marcus_sommer]

If-Statements are always slow. But you could try it with conditions on the expressions - this means you have no nested if then only the expression(s) with a valid condition will be displayed.

- Marcus

[Clever_Anjos]

alt(exp1,exp2,exp3,exp4,'Unknow')

[#7]

does alt only work on numbers?

[Clever_Anjos]

Yes

[#9]

Is alt significantly faster than a nested if?  I can probably convert the field i'm working with to duals, allowing alt to work on them but return the strings I need.

[Clever_Anjos]

I´ve never tested speed of both.

I generally use it because is much 'cleaner' to read and mantain