如果给定的值是个数组,那么该数组被看做是一个元素,添加给定字段中(If the value is an array, $push appends the whole array as a single element)。 格式: { $push: {<field1>:<value1>, ... } } 举例: 添加一个分数到成绩数组中: db.student.update({_id:1}, {$push : {scores:91}});...
db.students.updateOne( { _id: 1 }, { $pop: { scores: -1 } } ) 执行后变为: { _id: 1, scores: [ 9, 10 ] } $pull:从现有数组中删除一个或多个与指定条件匹配的值的所有实例。 { $pull: { <field1>: <value|condition>, <field2>: <value|condition>, ... } } 例子: db.sto...
官方的说明、Demo地址:https://www.mongodb.com/docs/manual/tutorial/query-array-of-documents/ 1.2 使用$elemMatch操作符查询,本文侧重该方式。 官方说明:The$elemMatchoperator matches documents that contain an array field with at least one element that matches all the specified query criteria. 就是说$...
The $pull operator removes from an existing array all instances of a value or values that match a specified condition. 1. 比如下面一条语句:更新 "_id" 为1 且将 votes数组中 大于等于6的所有vote 都删除。 #{ _id: 1, votes: [ 3, 5, 6, 7, 7, 8 ] } 1. db.profiles.update( { _...
db.movies.updateOne( {"title":"Traffic in Souls"}, { $push: {"languages":"French"} }//languages字段已存在,追加 -> languages: ["French"]) 如果想向数组中一次添加多个值,需配合$each ,$push : {<field_name> : {$each : [<element 1>, <element2>, ..]}} ...
To project, or return, an array element from a read operation, see the $ projection operator instead. To update all elements in an array, see the all positional operator $[] instead. To update all elements that match an array filter condition or conditions, see the filtered positional operat...
condition = {'age': {'$gt': 20}} result = collection.update_one(condition, {'$inc': {'age': 1}}) print(result) print(result.matched_count, result.modified_count) 这里指定查询条件为年龄大于20,然后更新条件为{'$inc': {'age': 1}},也就是年龄加1,执行之后会将第一条符合条件的数据年...
Update Statements Each element of the updates array is an update statement document. Each document contains the following fields: Field Type Description q document The query that matches documents to update. Use the same query selectors as used in the find() method. u document or pipeline The ...
How to update objects in the document array in MongoDB? We can use the$positional operator in combination with theupdateOne()orupdateMany()method to update objects in an array in MongoDB. The$positional operator allows us to update the first array element that matches a particular condition. ...
$: Acts as a placeholder to update the first element that matches the query condition in an update. 示例1,使用empty filter作为query filter db.users.updateMany( {}, {$inc:{"comments..unlikes":1}} ) MongoDB抛出错误消息: "errmsg" : "The positional operator did not find the match needed...