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法律研究如何在 MongoDB 中更新所有文档？
你可以使用 updateMany() 来更新文档。我们创建一个包含文档的集合。创建包含文档的集合的查询如下 −
> 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")
}使用 find() 方法显示集合中的所有文档。查询如下 −
> db.updateManyDocumentsDemo.find().pretty();
输出如下 −
{
"_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"
}以下是对所有文档进行更新的查询。用 “StudentFirstName” 更新 “StudentName” −
> db.updateManyDocumentsDemo.updateMany({}, {$rename: {'StudentName': "StudentFirstName"}});输出如下 −
{ "acknowledged" : true, "matchedCount" : 4, "modifiedCount" : 4 }检查文档是否已被更新。查询如下 −
> db.updateManyDocumentsDemo.find().pretty();
输出如下 −
{
"_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"
}
更新日期：2019-07-30
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