"Length" : "4:15" } ] } ] > db.mediaCollection.find( { Cast : {$size : 1} } ).toArray() [ ] > db.mediaCollection.find( { Cast : {$size : 6} } ).toArray() [ { "_id" : ObjectId("53548225d85b463e729a2e57"), "Type" : "DVD", "Title" : "Matrix, The", "Rel...
下面的语句就可以匹配:db.things.find( { a : { $size: 1 } } ); 官网上说不能用来匹配一个范围内的元素,如果想找$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 $size to find a range of sizes (for example: arrays with more than 1 element). If you need to query...
"namespace":"mldn.students","indexFilterSet":false,"parsedQuery":{"age":{"$eq":19}},"winningPlan":{"stage":"FETCH","inputStage":{"stage":"IXSCAN","keyPattern":{"age":-1},"indexName":"age_-1","isMultiKey":false,"multiKeyPaths":{"age":[]},"isUnique":false,"isSparse":fal...
db.qtfm__audio_info.find({playLength:{$gt:2}}) 小于($lt):Less than,值类型需要为int、double... db.qtfm__audio_info.find({playLength:{$lt:2}}) 大于等于($gte):Greater than equals db.qtfm__audio_info.find({playLength:{$gte:2}}) 不等于($ne):Not equals db.qtfm__audio_info.f...
.sort({ name: 1 }) .toArray() .then(items => { console.log(`Successfully found ${items.length} documents.`) items.forEach(console.log) return items }) .catch(err => console.error(`Failed to find documents: ${err}`)) 参数 find( query?: object, projection?: object, options?: ...
从MongoDB 3.6 及更高版本开始,查询$type: array返回字段本身是数组的文档。但是,在使用相同的查询时,以前的版本用于返回字段是数组的文档,并且至少一个元素是数据类型数组。 数组运算符 MongoDB 还包含数组运算符,用于查询包含数组的文档。 有三个主要运算符$all:$elemMatch和$size。我们将在下面详细讨论每一个。
Unwind Array Values 您可以使用$unwind阶段将包含数组的单个文档转换为包含该数组中各个值的多个文档。当您展开数组字段时,MongoDB 会为该数组字段的每个元素复制每个文档一次,但同时还会在每个副本中用数组元素替换数组值。 { $unwind: { path: <Array Field Path>, ...
51. 52. 53. 54. 55. 56. 57. 58. 59. 60. 61. 62. 63. 64. 65. 66. 67. 68. 15. $type 根据BSON类型来检索集合中匹配的结果。 MongoDB中可以使用的类型如下表所示: 类型描述 类型值 Double 1 String 2 Object 3 Array 4 Binary data 5 Object id 7 Boolean 8 Date 9 Null 10 Regular...
"<array>.<index>" 1. 例如存在以下文档: { ... contribs: [ "Turing machine", "Turing test", "Turingery" ], ... } 1. 2. 3. 4. 5. 访问contribs数组第三个元素"Turingery"的表达式为: "contribs.2"。 For examples querying arrays, see: ...
The following example queries for all documents where the second element in the arraydim_cmis greater than25: db.inventory.find( {"dim_cm.1": {$gt:25} } ) Query an Array by Array Length Use the$sizeoperator to query for arrays by number of elements. For example, the following select...