The API isn't set in stone at all. Frankly, what I really have is an engine and I'm kinda looking for someone to tell me what existing module I should graft my engine into. Maybe Class::DBI is the correct place to offer this as a patch to. It seems to be the most well-used RDBMS distro behind DBI/DBD::* ...

As for only allowing one path through the table schema ... that's actually been a problem I've run into. Behind the scenes, I build a graph of the schema, then walk the graph to find the correct connections. Let's say you have the following schema: 

movie:
    id       integer
    name     varchar
    director integer foreign key director.id

director:
    id     integer
    person integer foreign key person.id
    salary float

roles:
    movie  integer foreign key movie.id
    person integer foreign key person.id
    type   enum ('lead', 'supporting', 'bit')

person:
    id   integer
    name varchar

[download]

Now, let's say you want to get the names of the director and lead for a given movie. If I were hand-building the SQL, I would do the following: 

SELECT d_p.name AS director_name
      ,l_p.name AS lead_name
  FROM movie m
  JOIN director d ON (d.id = m.director)
  JOIN person d_p ON (d.person = person.id)
  JOIN roles r ON (r.movie = movie.id)
  JOIN person l_p ON (r.person = person.id)
 WHERE movie.name = ?
   AND r.type = 'lead'

[download]

Right now, the engine I have isn't smart enough to realize that I need to use the person table twice. Part of the problem there is the API. I don't know how to allow the user to specify "Join to person through director and alias it as d_p" as well as "Join to person through roles and alias it as l_p".

*ponders*

Maybe, the aliases are specified as part of the schema description. So, if you use a given alias for a table, it's joined through one path and if you use the other, a second join (like above) is made through the other path. I think I can code this up, but I'd really love to have a good set of requirements ... (Hint!)

Being right, does not endow the right to be rude; politeness costs nothing.
Being unknowing, is not the same as being stupid.
Expressing a contrary opinion, whether to the individual or the group, is more often a sign of deeper thought than of cantankerous belligerence.
Do not mistake your goals as the only goals; your opinion as the only opinion; your confidence as correctness. Saying you know better is not the same as explaining you know better.

In reply to Re^2: RFC - A multi table SQL Builder by dragonchild
in thread RFC - A multi table SQL Builder by dragonchild

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.