Database connection confusion

Hi, ALL,
On the page it says:

Quote:

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SQL_USER_NAME(ODBC 1.0)
A character string with the name used in a particular database, which can be different from the login name.

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However, this page uses this in the example to (presumably) retrieve the user connected to the DB.

Does the sample implies that I can use such technique? Or this is merely a sample?

If its the latter - what condition would trigger an inconsistency the first page is referencing? Or this is for ODBC v1/v2 and in version 3 this works consistently across different DB vendors?

I'm actually looking for a username which has a current connection (or the one that currently connected to the DB).

Thank you.