Selection set logic

[Nancy Palmquist]

Shane Gray wrote:
> I've noticed an issue in the past, but not spent time checking, with
> selection sets, in particular the selector sentence.
> 
> Consider the following selection set:
> 
>  Group   Field  Heading                 Rel    Value  
> ------------------------------------------------------
>                                                       
>  a      .  1  . Branch                  ge .   QL.    
>  b      .  1  . Branch                  le .   SS.    
>  c      .  1  . Branch                     .   AA.    
>         .     .                            .          
>                                                       
> ------------------------------------------------------
> Selector Sentence:                                    
> a and b or c                                          
> 
> I believe the selector sentence should evaluate the same as "(a and b) or c"
> giving a result with all the branch codes from QL to SS as well as AA.  
> 
> It would however seem to evaluate the same as "a and (b or c)" giving a
> result with only branch codes between QL and SS.  No AA.
> 
> I have confirmed this by actually putting the parentheses in for both
> options.  Is it that the selector sentence doesn't follow order of
> precedence?
> 
> I have tested this up to 5.0.14 on SCO rclerk/rreport.  
> 
> Can anyone confirm this is an issue (or alternately that I am an imbecile).
> I could of course be just using it incorrectly.
> 
Selector sentence follows Boolean order if you do not use parenthesis.  It is 
not LEFT to RIGHT.  I know this but I do not remember which is first AND or OR. 
  I know NOT would be applied first, then as I think AND would be applied second 
then OR last.

Since my memory is always confused, I always use parenthesis to insure it does 
what I want.

I hate to leave defaults that could have a different agenda than I do.

In Conclusion, a and b or c is the same as (a and b) or c

But is not the same as a and (b or c)


Nancy



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