> For the complete documentation index, see [llms.txt](https://docs.mongoing.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.mongoing.com/can-kao/yun-suan-fu/query-and-projection-operators/ying-she-yun-suan-fu.md).

# 映射运算符