mongos> var it = db.test.find({'i': 1, "old_id": {$exists: 1}}) 遍历计数1:mongos> var count = 0;while(it.hasNext()){if (it.next()["X"].length==32)++count}print(count) 遍历计数2:mongos> var count = 0;while(it.hasNext()){var item = it.next(); if (item['X']...
$exists {<key>:{$exists:<value>}}字段是否存在。 db.col.find( { item : { $exists: false } } ) 模糊查询 没有操作符,根据书写规则来决定是否是模糊查询。 和普通is查询一样,但是值需要加//。 like:{name:/小/} likeBegin: {name:/^小/} likeEnd:{name:/小^/} db.col.find( { item :...
document in the array in the given order, checking the authentication username against the match filter. if a match is found, mongod applies the transformation and uses the output for authenticating the user. mongod does not check the remaining documents in the array. if the given document ...
document Sets the shard key to generate on the destination cluster. shardingEntries .shardCollection .key array Sets the fields to use for the shard key. For more information, seeShard Keys. mongosyncthrows an error if theshardingoption is not set when syncing from a replica set to a sharded...
aliasDoctrine offers a way to alias document namespaces to simpler, shorter names to be used in queries or for Repository access. is_bundleThis option is a derived value fromdirand by default is set to true if dir is relative proved by afile_exists()check that returns false. It is false...
操作符效果 $exists 存在与否 $or 或者 $and 并且 $not 不存在 $mod 求模 $where 位置特别的 $exists: true 表示字段存在排序sort 操作效果 $asc 升序 $desc 降序3、更新文档 更新文档有两种方式进行修改 方法一、直接修改 db.集合名.update({条件},{新的文档}) :修改当前数据库下指定集合中满足条...
<cfscript> db = getmongoservice("mymongodb").db("newdb") // create a db db.createCollection("newcolThree") // create a collection // insert a single document db.newcolThree.insert({ "_id": 1, "name":"John Lennon", "band":"Beatles" }) </cfscript> Note: If you do not ex...
MongoDB waits until you have created a collection (table), with at least one document (record) before it actually creates the database (and collection). Check if Database Exists Remember:In MongoDB, a database is not created until it gets content, so if this is your first time creating...
Amazon DocumentDB (with MongoDB compatibility) is a fast, scalable, highly-available, and fully managed document database service that supports MongoDB workloads. Amazon DocumentDB is compatible with the MongoDB 3.6, 4.0, and 5.0 APIs. This section lists the supported functionality. For support usi...
MongoDB waits until you have inserted a document before it actually creates the collection.Check if Collection ExistsRemember: In MongoDB, a collection is not created until it gets content, so if this is your first time creating a collection, you should complete the next chapter (create ...