MongoDB如何进行多个原子更新？
对于多个原子更新，将update()与$set一起使用。让我们创建一个包含文档的集合-
> db.demo699.insertOne({Name:"Chris Brown"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5ea6e370551299a9f98c93a7")
}
> db.demo699.insertOne({Name:"David Miller"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5ea6e37a551299a9f98c93a8")
}
> db.demo699.insertOne({Name:"Chris Brown"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5ea6e381551299a9f98c93a9")
}
> db.demo699.insertOne({Name:"John Doe"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5ea6e38a551299a9f98c93aa")
}在find()方法的帮助下显示集合中的所有文档-
> db.demo699.find();
这将产生以下输出-
{ "_id" : ObjectId("5ea6e370551299a9f98c93a7"), "Name" : "Chris Brown" }
{ "_id" : ObjectId("5ea6e37a551299a9f98c93a8"), "Name" : "David Miller" }
{ "_id" : ObjectId("5ea6e381551299a9f98c93a9"), "Name" : "Chris Brown" }
{ "_id" : ObjectId("5ea6e38a551299a9f98c93aa"), "Name" : "John Doe" }以下是使用MongoDB执行多个原子更新的查询-
> db.demo699.update({Name:"Chris Brown"},{ $set : { Name: "Adam Smith"} }, false, true );
WriteResult({ "nMatched" : 2, "nUpserted" : 0, "nModified" : 2 })在find()方法的帮助下显示集合中的所有文档-
> db.demo699.find();
这将产生以下输出-
{ "_id" : ObjectId("5ea6e370551299a9f98c93a7"), "Name" : "Adam Smith" }
{ "_id" : ObjectId("5ea6e37a551299a9f98c93a8"), "Name" : "David Miller" }
{ "_id" : ObjectId("5ea6e381551299a9f98c93a9"), "Name" : "Adam Smith" }
{ "_id" : ObjectId("5ea6e38a551299a9f98c93aa"), "Name" : "John Doe" }