| Re: SQL access without Dataminer [message #33979 is a reply to message #33927] |
Tue, 11 February 2003 16:44   |
Randall Skelton
Messages: 169
Registered: October 2000
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Senior Member |
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I have written some very raw DLMs that emulate postgres' libpq functions.
The library is in a bit of a state of flux as I have been slowly adding
multi-threaded connection support, blobs, and vectorizing. It works under
*nix.
There are very general problems involved when you start desiring
cross-platform database access. Firstly, you need to be careful
about binary conversions or simply stick to ascii returns. Secondly,
while ODBC/JDBC are the obvious choices for communication, last time I
checked there weren't any free cross-platform libraries. Both of the
above libraries provide hooks for easy casting which is a real pain to
sort out with the raw C libraries for postgres and mysql. That being
said, I quite like the speed I can get out of my libpq wrappers when used
in multi-threaded mode ;) The OBDC drivers for postgres cannot compare.
The short answer is that while $500 US seems like a lot up front, anyone
who thinks they can write a database interface for less (time=$$$) is
probably kidding themselves. It took me 2 weeks to get version 1 of my
postgres DLM working and the interface is nowhere near as easy to use as
the dataminer. I don't even want to begin adding up the hours of bug
fixing, vectorizing, trapping that I've done since version 1.
>> Does anyone know if IDL has any SQL access capability without purchasing
>> Dataminer? Are there any freeware SQL interface libraries for IDL?
Yes. I can send you my postgres DLMs if you wish. They work for *nix and
are sent as source for you to compile.
> I'm interested in this too. I have some IDL -> Database -> Web
> applications in mind, so I started to learn PHP and MySQL, which are
> both pretty easy to use (and free!) Plus, they have very nice (also
> free) web-based administration programs out there. The IDL DataMiner
> (~$500 US) claims support for SQL and ODBC. Without too much
> investigation, it seems to me that the core SQL grammar and MySQL
> grammar are similar if not identical.
They are subtly different. The debate regarding the level of SQL
compliance is too detailed to get into here. Each of the big 3
(postgersql, mysql, oracle) has their own syntax quirks and their own
low-level programming APIs. This is why OBDC and JDBC are popular.
> I haven't tested the overlap of
> the database-connection methods between the two, but they must be
> somewhat similar.
Their APIs are all similar as they each provide database access but
they are completely independent C/C++ libraries.
> In my opinion, it would be great if IDL DataMiner would support MySQL
> explicitly (how hard could it be for them to do this?). Failing that,
> it may be possible to develop some PHP code from the command line to
> take SQL/MySQL queries generated within IDL and return results
> somehow.
OBDC/JDBC are designed as abstractions libraries and and provide a
standard interface. Developers for each database simply emulate the OBDC
functionality using a subset of their own raw libraries. You could very
well write DLM wrappers around the mysql C libraries to get the same
functionality that I have with postgres.
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