Add support for SQLSetConnectAttr - SQL_ATTR_APP_UNICODE_TYPE, SQL_ATTR_DRIVER_UNICODE_TYPE, SQL_ATTR_APP_WCHAR_TYPE

[epDugas]

This idea stems from this issue
where the resolution to that issue involved surfacing the ability to set the payload encoding type (8.3.0).

While researching @pacman82 's initial suggested action of specifying the driver, to use utf-8, I came across the below information. *My knowledge of ODBC is limited, especially in the realm of unicode and cross platform differences in handling. I do not know what effect setting any of these particular SQLSetConnectAttr attributes would have had, just surfacing for discussion in case they could have been of any relevance for my particular situation. *

Driver Manager and Unicode encoding on UNIX/Linux

Understanding Unicode and ODBC Data Access

What are the semantics of SQL_ATTR_APP_UNICODE_TYPE, SQL_ATTR_DRIVER_UNICODE_TYPE, and SQL_ATTR_APP_WCHAR_TYPE?

Would it make any sense to expose setting these values, to accommodate differing unicode handling on linux/unix platforms?

Look forward to any feedback and anything I may learn from it.

Thanks,
Eric

[pacman82]

Hello @epDugas ,

nice of you to look for more fundamental solutions, but I fear you googled documentation only applying to Drivers written by Data Direct.

In the context of your problem. My guess is the driver would not have understood these flags.

You could verify your systems local is indeed using UTF-8 and open a bug with unixODBC or Oracle why the returned encoding differed.

This is the documentation I would consider: https://learn.microsoft.com/en-us/sql/odbc/reference/develop-app/unicode?view=sql-server-ver16

Best, Markus

[epDugas]

Thanks for the feedback Markus. I guess I jumped the gun and didn't consider that. I found direct reference to it when I grepped the driver files, but there is also lots of verbiage in there that reference DataDirect, including some C examples on using the driver, guessing it is assuming use through DataDirect driver manager.
Interestingly, SQL_ATTR_APP_UNICODE_TYPE is mentioned in unixOdbc, but looks like a no-op.

Just adding a couple of notes after some additional findings, in case someone stumbles on to this looking for info:

This particular driver was created with Progress Open Access SDK, and ships with an included proprietary Driver Manager (DataDirect). The DataDirect driver manager supports numerous non-standard flags that can be set through calls such as SQLSetConnectAttr.

Thanks again,
Eric

[pacman82]

Hi @epDugas , thanks for the additional context. I am not sure if we'll ever see an ODBC 4.0 standard coming to life, but I am sure most people would have realized by then that UTF-8 is a good choice. In the meanwhile, more and more system locals are UTF-8 by default and less and less Database managment systems would return text in anything but UTF-8. So time is on our side.

Best, Markus