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From: Phil Endecott (spam_from_boost_dev_at_[hidden])
Date: 2007-03-15 10:26:10

> Choosing C++ for a projects where databases are involved is probably
> rare

Well it's what I spend quite a lot of my time doing, and I find it a
good combination. But then I often seem to be doing things differently
from everyone else...

In my case I have written a C++ binding for PostgreSQL's libpq which
allows me to define queries as functors:

Query<string,int> insert_thing(db, "insert into things(name,qty) values ($1,$2)");
SingletonQuery<int, string> count_things(db, "select sum(qty) from
things where name=$1");

int n_pens = count_things("pen");

Note the template type parameters in the query declarations. These
give the C++ types corresponding to the $n parameter placeholders in
the SQL, and are mapped to the "oids" (in postgresql-speak) of the
corresponding SQL types. The queries are prepared, and when they are
run the parameters are passed to the database server in binary format.
You get compile-time checking that the types in the query invocations
match those in the declarations and run-time checking that the backend
is happy with those types.

I like this approach as it gives about as much type safety as is
possible and lets you do database accesses with essentially the same
syntax that you would use to access C++ data. I prefer this to the way
that SOCI is used, where you always know that you're using SQL (though
SOCI no doubt has other features that my library is missing).

There is more detail here:

I would be happy to describe my experiences further if anyone is
considering adding something along these lines to Boost. My code is
currently GPL but I am flexible about that.



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