Changes the application's NCHAR character set for this connection. Data sent and fetched using DT_NFIXCHAR, DT_NVARCHAR, DT_LONGNVARCHAR,
and DT_NSTRING host variable types are in the NCHAR character set.
If the db_change_nchar_charset function is not called, all data is sent and fetched using the CHAR character set. Typically,
an application that wants to send and fetch Unicode data should set the NCHAR character set to UTF-8.
If this function is called, the charset parameter is usually "UTF-8". The NCHAR character set cannot be set to UTF-16.
In embedded SQL, NCHAR, NVARCHAR and LONG NVARCHAR are described as DT_FIXCHAR, DT_VARCHAR, and DT_LONGVARCHAR, respectively,
by default. If the db_change_nchar_charset function has been called, these types are described as DT_NFIXCHAR, DT_NVARCHAR,
and DT_LONGNVARCHAR, respectively.