The Driver Manager, not the ANSI driver, must convert SQL_C_WCHAR (Unicode) data to SQL_CHAR (ANSI) data, and vice versa (see "Unicode Support in ODBC" for a detailed discussion). This is necessary because ANSI drivers do not support any Unicode ODBC types.

The Driver Manager must use client code page information (Active Code Page on Windows and the IANAAppCodePage attribute on UNIX/Linux/macOS) to determine which ANSI code page to use for the conversions. The Active Code Page or IANAAppCodePage must match the database default character encoding. If not, conversion errors are possible.