On Monday, 8 October 2012 at 10:26:35 UTC, denizzzka wrote:
On Monday, 8 October 2012 at 07:35:13 UTC, Paulo Pinto wrote:
On Sunday, 7 October 2012 at 20:05:22 UTC, denizzzka wrote:
On Sunday, 7 October 2012 at 17:06:31 UTC, Joseph Rushton
Wakeling wrote:
On 10/07/2012 10:55 AM, Russel Winder wrote:
Why only PostgreSQL. Shouldn't it also work with MySQL,
Oracle, DB2,
PervasiveSQL, SQLite3, etc.?
I don't have sufficient experience with SQL to be able to
really make a judgement here, but is there a case for a
std.sql or std.db that would provide a uniform D interface
to the arbitrary DB of choice?
Each database engine has a unique distinguishing features
that make this engine interesting. (for example, different
implementations of transactions - SQL standard does not
describe the SQL transactions precisely enough)
There are plenty of existing interfaces to base D's design on,
just a few of them:
Perl - DBI
Python - DB API
C, C++ - ODBC (there is an UNIX variant of it)
C++ - OLE DB (Although Windows specific)
Java - JDBC
.NET - Data Providers
Ruby - DBI
TCL - TDBC
Go - database package
Delphi - Data Access
Haskell - HaskellDB (HDBC)
So, I do not know is it possible to make a universal
interface. And why it may need in real life?
At least in the enterprise world, we tend to write
applications in a DB independent way.
One reason is to be able to deploy the applications without
forcing the customers to invest in new DB engines, thus
reaching a broader client base.
Sometimes inside the same organization different business
units have different DB engines running (even different
versions of the same DB).
Finally, to minimize costs when management decides for
whatever reason, to change the DB licenses being used.
--
Paulo
For this to work you need to implement an independent way to
create queries that would work on all database engines the same
way. I believe that this problem is in principle much more
complicated than it would have been implemented interfaces to
databases in separate libs.
Sure. That is why on top of a DB driver layer, usually you have
some kind of SQL adaptation layer.
On the TCL/C abstraction layer we implemented for a product
during the 1999-2001 timeframe, we used standard SQL '92 for all
data queries, regardless of hand-written or generated from our
TCL ORM.
Then there was a translation layer that transformed SQL '92 into
DB specific SQL, before giving it to the corresponding driver.
The only two parts of the application that had DB specific code
were the SQL transformation layer, and the .so/.dll with the DB
specific driver.
With the added benefit that any DB fully SQL '92 compliant did
not need any adaptations in the transformation layer.
--
Paulo
