官网上说不能用来匹配一个范围内的元素,如果想找$size<5之类的,他们建议创建一个字段来保存元素的数量。 You cannot use $size to find a range of sizes (for example: arrays with more than 1 element). If you need to query for a range, create an extra size field that you increment when you ...
To store the access criteria data, add a field to the documents and embedded documents. To allow for multiple combinations of access levels for the same data, consider setting the access field to an array of arrays. Each array element contains a required set that allows a user with that set...
You cannot use $size to find a range of sizes (for example: arrays with more than 1 element). If you need to query for a range, create an extra size field that you increment when you add elements. 7)$exists $exists用来判断一个元素是否存在: 如: db.things.find( { a : { $exists...
如果没有Collation指定在集合或者操作上,MongoDB对于字符串的比较跟以前版本一样,都是简单二进制对比。 Arrays:对于数组的比较,如果是小于或者升序比较,比较数组中的最小元素。如果是大于或者降序比较,比较数组中的最大元素。 空数组小于非空数组。 Dates and Timestaps:3.0.0版本之前两者同时排序,之后Date对象优先于T...
MongoDB Manual code examples for how to query an array of documents, including nested or embedded documents.
You cannot use $size to find a range of sizes (for example: arrays with more than 1 element). If you need to query for a range, create an extra size field that you increment when you add elements. 7)$exists $exists用来判断一个元素是否存在: ...
public array batchInsert ( $rows, $options = [] ) $rows array Array of arrays or objects to be inserted. $options array List of options in format: optionName => optionValue. return array Inserted data, each row will have "_id" key assigned to it. throws yii\mongodb\Exception on fai...
includeArrayIndex string 可选,定义返回的字段名,返回的值是拆分前值在原数组的位置 preserveNullAndEmptyArrays boolean 可选,配置在path的值为空或缺失的情况下是否拆分, 默认false 示例: 假设articles文档集合是这样: 代码语言:javascript 复制 { title: 'this is article A', author: 'John', _id: 1, com...
该名称不能以$开头。includeArrayIndex: <string>,#可选,default :false,若为true,如果路径为空,缺少或为空数组,则 $unwind输出文档preserveNullAndEmptyArrays: <boolean>} } 姓名为xx006的作者的book的tag数组拆分为多个文档 db.books2.aggregate([{$match:{"author.name":"xx006"}},{$unwind:"$tag"}]...
增加icludeArrayIndex,preserveNullAndEmptyArrays两个可选配置 { $unwind: { path:<field path>, includeArrayIndex:<string>, preserveNullAndEmptyArrays:<boolean>} } 示例:# 假设articles文档集合是这样: { title:'this is article A', author:'John', _id:1, comments: ['a','b','c']} ...