From: Charles Mills <cmills@...>
Date: 2004-12-18T03:22:11+09:00
Subject: Re: String expand problem


Austin Ziegler wrote:
(snip)
> If you've ever done Oracle programming using Pro*C, this is
equivalent to doing:
>
>    SELECT foo, bar
>      FROM baz
>     WHERE oingo = :boingo;
>
> It results in far more efficient SQL most of the time, because the
> optimizers in quality databases (e.g., most emphatically *not* MySQL)
> will detect that all queries referring the ? or :boingo can be
> optimized and compiled a particular way so that only the parameters
> vary and the SQL doesn't have to be recompiled every time you provide
> a new value for :boingo :)
>

SQLite allows this as well (using ':name' as a place holder).  Since
the place holder looks like a symbol it seems natural to allow the
following (in Ruby DBI and other Ruby database drivers):

db.execute("select * from table where field = :yada", :yada =>
my_string)

Anyway, using symbols and the hash in the parameters list thing you end
up with some nice syntactic sugar.  Clearer than using positional place
holders (IMO).

-Charlie