Function SQLGetDiagFieldW 

pub unsafe extern "system" fn SQLGetDiagFieldW(
    handle_type: HandleType,
    handle: Handle,
    record_number: SmallInt,
    diag_identifier: SmallInt,
    diag_info_ptr: Pointer,
    buffer_length: SmallInt,
    string_length_ptr: *mut SmallInt,
) -> SqlReturn

Returns the current value of a field of a record of the diagnostic data structure (associated with a specified handle) that contains error, warning, and status information.

Note: diag_identifier is either SqlHeaderDiagnosticIdentifier or SqlDynamicDiagnosticIdentifier

Returns

SUCCESS, SUCCESS_WITH_INFO, ERROR, INVALID_HANDLE, or SQL_NO_DATA.