如何更新MongoDB中的所有文档？
您可以updateMany()用来更新文档。让我们用文档创建一个集合。使用文档创建集合的查询如下-
> db.updateManyDocumentsDemo.insertOne({"StudentName":"John","StudentLastName":"Smith"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c948edd4cf1f7a64fa4df48")
}
> db.updateManyDocumentsDemo.insertOne({"StudentName":"John","StudentLastName":"Doe"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c948ee64cf1f7a64fa4df49")
}
> db.updateManyDocumentsDemo.insertOne({"StudentName":"Carol","StudentLastName":"Taylor"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c948ef14cf1f7a64fa4df4a")
}
> db.updateManyDocumentsDemo.insertOne({"StudentName":"David","StudentLastName":"Miller"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c948f044cf1f7a64fa4df4b")
}在find()method的帮助下显示集合中的所有文档。查询如下-
> db.updateManyDocumentsDemo.find().pretty();
以下是输出-
{
"_id" : ObjectId("5c948edd4cf1f7a64fa4df48"),
"StudentName" : "John",
"StudentLastName" : "Smith"
}
{
"_id" : ObjectId("5c948ee64cf1f7a64fa4df49"),
"StudentName" : "John",
"StudentLastName" : "Doe"
}
{
"_id" : ObjectId("5c948ef14cf1f7a64fa4df4a"),
"StudentName" : "Carol",
"StudentLastName" : "Taylor"
}
{
"_id" : ObjectId("5c948f044cf1f7a64fa4df4b"),
"StudentName" : "David",
"StudentLastName" : "Miller"
}这是更新所有文档的查询。“StudentName”更新为“StudentFirstName”-
> db.updateManyDocumentsDemo.updateMany({}, {$rename: {'StudentName': "StudentFirstName"}});以下是输出-
{ "acknowledged" : true, "matchedCount" : 4, "modifiedCount" : 4 }检查文档是否已更新。查询如下-
> db.updateManyDocumentsDemo.find().pretty();
以下是输出-
{
"_id" : ObjectId("5c948edd4cf1f7a64fa4df48"),
"StudentLastName" : "Smith",
"StudentFirstName" : "John"
}
{
"_id" : ObjectId("5c948ee64cf1f7a64fa4df49"),
"StudentLastName" : "Doe",
"StudentFirstName" : "John"
}
{
"_id" : ObjectId("5c948ef14cf1f7a64fa4df4a"),
"StudentLastName" : "Taylor",
"StudentFirstName" : "Carol"
}
{
"_id" : ObjectId("5c948f044cf1f7a64fa4df4b"),
"StudentLastName" : "Miller",
"StudentFirstName" : "David"
}