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From: Stephen Leake <stephen_leake@stephe-leake.org>
Newsgroups: comp.lang.ada
Subject: Re: GNATCOLL.SQL.SQL_Select - I'm in Left_Join hell
References: <4f90233d$0$282$14726298@news.sunsite.dk>
Date: Sat, 21 Apr 2012 08:02:14 -0400
Message-ID: <82vckti989.fsf@stephe-leake.org>
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Date: 2012-04-21T08:02:14-04:00
List-Id: <comp.lang.ada>

Thomas Løcke <thomas@12boo.net> writes:

> https://gist.github.com/2421241
>
> It is, IMHO, very unreadable with all those nested Left_Join calls. Is
> there a better/prettier way, without falling back to embedding an SQL
> string in the Ada source?

> The SQL generated by the above SQL_Select call works fine, it's just
> that I'm finding it very hard to read.

You could do each Left join in separate statements before the
SQL_Select, and pass the final table to SQL_Select.

or use named association to reorder the lines:

  Left_Join
      (Full => Organization,
       On   => Organization.Org_Id = Contactentity_Organization.Org_Id,
       Partial => Left_Join
         (Full => Contactentity_Organization,
          On   => Contactentity.Ce_Id = Contactentity_Organization.Ce_Id,
          Partial => Left_Join
            (Full => Contactentity,
             On   => Contactentity.Ce_Id = Contactentity_Tag.Ce_Id,
             Partial => Left_Join
               (Contactentity_Tag,
                Tag,
                Tag.Tag_Id = Contactentity_Tag.Tag_Id)))),

I don't like the 'full' and 'partial' names, but this looks a little better.
   
-- 
-- Stephe