Subject: Re: [boost] SQL client library ?
From: Allan Wind (allan_wind_at_[hidden])
Date: 2009-09-16 17:50:57
On 2009-09-16T20:12:13, Jean-Louis Leroy wrote:
> Like this :
> select((t1.id, t2.id)).from((t1, t2, p))
> .where((t1.income + t2.income).between(20, 40)
> && p.husband == t1.id && p.wife == t2.id)
I recently played with most of the perl modules to generate SQL,
and none really worked well for some semi-fancy reporting
On one hand I wanted a data structure so I could build a query
dynamically: add column X to the select and group by expression,
then do it for Y. Here is a collection of conditions for the
where clause which should be 'AND'ed together etc.
However if you build your entire query you are forced into using
this new API even if most of features add no value, or when it
adds overhead to something you can easily just type out:
"select count(*) from tbl"
"select (select max(value) from tbl1 where tbl1.id = tbl2.id) from tbl2 where ... group by tbl2.name"
It would be great if you could start with a string of SQL, have
the library parse it and provide features to refine expressions.
Let the library optionally bind and escape values. Provide
control over how the output should be normalized (case of
keywords, sub query indent, field separators etc), and allow the
SQL to be dumped. mysql, for instance, caches the exact string
of the query.
The SQL generation library should be separate from whatever talks
to the database. You may not need to talk to the database, or
there might be lots of magic with database handlers (load
balancing, pooling, keep-alive etc).
I hope it helps.
-- Allan Wind Life Integrity, LLC <http://lifeintegrity.com>
Boost list run by bdawes at acm.org, gregod at cs.rpi.edu, cpdaniel at pacbell.net, john at johnmaddock.co.uk