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  3. November 2005

Re: Yet another SQL newbie question

I'm not sure exactly what you're after James, but you can do explicit subqueries and use them as part or all of the main query with common table expressions more or less like this: 

with (fld1, fld2, fld3) a
  as (
   select xxfld1, xxfld2, xxfld3
   from table1
   where <stuff> ),
 ( fld4, fld5, fld6) b
  as (
   select zzfld4, zzfld5, zzfld6
   from table2
   where <morestuff> )
select c.x, c.y, c.z
 from table3 c
 join a
   on a.fld1 = c.x
  and a.fld2 = c.y
  and a.fld3 = c.z
 exception join b
   on b.fld4 = c.x
  and b.fld5 = c.y
  and b.fld6 = c.z
order by c.x
Very powerful stuff. You can even do summary functions in the common table expressions and use them as if they were scalar values. Not magic though. Just like everything else, if you string enough of it together, the lights dim in Boston if you're within the continental US.

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