Support unixodbc in Mac OSX

[jacobsvante]

This resolved the MemoryError issues that I had experienced with iODBC. It seems that others have this issue as well..

Btw what is the status of the pyodbc project? There's a lot of unanswered issues these days.

[mkleehammer]

I'm really uncomfortable with this idea. If I remember correctly before 10.7 iODBC was shipped with OS/X and was the obvious choice. Having it link in two different ways based on whether something installs seems like a very bad idea - if you use a requirements.txt file for a project, you want to know that it will always be built the same way.

I think adding a command-line option to the build is a great idea, but not doing it by default. Let me think about the different options. Thanks very much for this code.

[bradjasper]

Just as a data point this is something I'd be interested in as well. I'm using unixodbc and currently just maintaining my own fork.

[sptramer]

This is really critical for modern OS X - iODBC does not come pre-packaged anymore and the only homebrew package is for unixodbc. ports might still offer iodbc but it's hard to imagine anyone preferring it these days.

[mkleehammer]

Thanks. I like this, but I hope it doesn't cause a lot of issues with building since unixODBC doesn't actually ship with OS X.

[mkleehammer]

I should have known better than to merge here. Consider this still open though I'm not sure how to do so.

Anyway, I've just installed unixODBC 2.3.2 on a fresh Mavericks system. It builds fine and installs libodbc.dylib and libodbc.2.dylib. Neither of these is found using gcc -l. I'm not using macports, homebrew, or fink - just Xcode.

(Side note: Please don't reformat imports and comments in other people's projects when adding 2-3 lines.)

[jacobsvante]

I don't think you can reopen a merged PR, perhaps it's better to create a new one.

My install of unixodbc was on Mountain Lion using homebrew. On Mavericks I get the following from running gcc -lodbc2:

Undefined symbols for architecture x86_64:
  "_main", referenced from:
     implicit entry/start for main executable
ld: symbol(s) not found for architecture x86_64
collect2: error: ld returned 1 exit status