Returns FALSE on error, and an array upon success.
This function will return the list of available DNS (after calling it
several times). The
connection_id is required to be a valid ODBC
fetch_type can be one of two
constant types: SQL_FETCH_FIRST, SQL_FETCH_NEXT. Use SQL_FETCH_FIRST the
first time this function is called, thereafter use the SQL_FETCH_NEXT.