dual with statement

[Jay Norwood via Digitalmars-d-learn]

On Friday, 25 July 2014 at 01:54:53 UTC, Jay Norwood wrote:
> I don't recall the exact use case for the database expressions, 
> but I believe they were substituting a simple symbol for the 
> fully qualified object.

The sql with clause is quite a bit different than I remembered.  
For one thing, I have the order reversed, so it would have been 
with (a as something.x.y).

It looks more like they are more like creating a temporary tuple 
from some more complicated selection.  It isn't clear what the 
implementation is, but just the that it might be a more concise 
way of stating things so that the expressions inside the body can 
be simple

So, my prior example
   with (ar.rm.a as d) with (ar.rm.b as e) with (ar.r.a as a) with
(ar.r.b as b) with (ar.r.c as c){
      d = a + c;
      e = (c==0)?0:(a+b)/c;
}


would reduce to something maybe simpler to read.  The sql seems 
to be using this as a foreach type operation, but I was just 
interested in the name substitution so that the expressions 
inside the with block could be simpler, as well as get rid of the 
struct member name clashes.

with ( (d,e,a,b,c) as (ar.rm.a, ar.rm.b, ar.r.a, ar.r.b, ar.r.c)){
      d = a + c;
      e = (c==0)?0:(a+b)/c;
}