notes.txt

Unicode
-------

http://support.microsoft.com/default.aspx?scid=kb;EN-US;q294169

    """
    For many of these Unicode functions, the ODBC Programmer's Reference provides incorrect or
    ambiguous descriptions for some of the function arguments. Specifically, this problem
    relates to arguments that are used to specify the length of character string input and
    output values."

    Regardless of what the documentation says for each ODBC function, the following paragraph
    from the Unicode section of "Chapter 17: Programming Considerations" in the ODBC
    Programmer's Reference is the ultimate rule to use for length arguments in Unicode
    functions:

        "Unicode functions that always return or take strings or length arguments are passed as
        count-of-characters. For functions that return length information for server data, the
        display size and precision are described in number of characters. When a length
        (transfer size of the data) could refer to string or nonstring data, the length is
        described in octet lengths. For example, SQLGetInfoW will still take the length as
        count-of-bytes, but SQLExecDirectW will use count-of-characters."

    This means that if the argument in question describes the length of another argument that
    is always a string (typically represented as a SQLCHAR), then the length reflects the
    number of characters in the string. If the length argument describes another argument that
    could be a string or some other data type (typically represented as a SQLPOINTER), the
    length is in bytes.
    """


Driver Support"

  * PostgreSQL seems to correct use UCS-2.
    http://archives.postgresql.org/pgsql-odbc/2006-02/msg00112.php

  * MS SQL Server on Windows & Linux.  Obviously correctly uses UCS-2.  SQL
    Server 2012 and higher now support UTF16.

  * mysql: Seems to be broken.  To handle this, probably need to provide a 'charset' option
    that causes us to convert to the given charset and use the ANSI/ASCII calls and data types.

    http://mysqlworkbench.org/?p=1399

  * FreeTDS

    http://www.freetds.org/userguide/unicodefreetds.htm
  
    Definitely use 0.91 or later.

    Have seen reference to a new --wide-unicode flag for 0.92+ (broken in 0.91) which causes
    SQL_WCHAR to equal wchar_t instead of UTF16.