在 MongoDB 中使用 $push
我们使用文档创建一个集合 −
> db.demo738.insertOne({Subjects:["C","C++"]}); { "acknowledged" : true, "insertedId" : ObjectId("5ead696557bb72a10bcf0661") } > db.demo738.insertOne({Subjects:["MySQL","PL/SQL"]}); { "acknowledged" : true, "insertedId" : ObjectId("5ead696657bb72a10bcf0662") }
使用 find() 方法从集合中显示所有文档 −
> db.demo738.find();
将会产生以下输出 −
{ "_id" : ObjectId("5ead696557bb72a10bcf0661"), "Subjects" : [ "C", "C++" ] } { "_id" : ObjectId("5ead696657bb72a10bcf0662"), "Subjects" : [ "MySQL", "PL/SQL" ] }
以下是 push 查询 −
>db.demo738.update({_id:ObjectId("5ead696657bb72a10bcf0662")},{$push:{"Subjects":"MongoDB"}}); WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
使用 find() 方法从集合中显示所有文档 −
> db.demo738.find();
将会产生以下输出 −
{ "_id" : ObjectId("5ead696557bb72a10bcf0661"), "Subjects" : [ "C", "C++" ] } { "_id" : ObjectId("5ead696657bb72a10bcf0662"), "Subjects" : [ "MySQL", "PL/SQL", "MongoDB" ] }
广告