MongoDB-更新部分文档？
要更新部分文档数量，请将multi设置为true。让我们创建一个包含文档的集合-
> db.demo312.insertOne({"FirstName":"Robert"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e50ce16f8647eb59e56204a")
}
> db.demo312.insertOne({"FirstName":"Bob"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e50ce19f8647eb59e56204b")
}
> db.demo312.insertOne({"FirstName":"Robert"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e50ce1cf8647eb59e56204c")
}
> db.demo312.insertOne({"FirstName":"David"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e50ce20f8647eb59e56204d")
}
> db.demo312.insertOne({"FirstName":"Robert"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e50ce22f8647eb59e56204e")
}在find()方法的帮助下显示集合中的所有文档-
> db.demo312.find();
这将产生以下输出-
{ "_id" : ObjectId("5e50ce16f8647eb59e56204a"), "FirstName" : "Robert" }
{ "_id" : ObjectId("5e50ce19f8647eb59e56204b"), "FirstName" : "Bob" }
{ "_id" : ObjectId("5e50ce1cf8647eb59e56204c"), "FirstName" : "Robert" }
{ "_id" : ObjectId("5e50ce20f8647eb59e56204d"), "FirstName" : "David" }
{ "_id" : ObjectId("5e50ce22f8647eb59e56204e"), "FirstName" : "Robert" }以下是更新部分文档的查询
> db.demo312.update({"FirstName":"Robert"},{$set:{"FirstName":"Sam"}},{multi:true});
WriteResult({ "nMatched" : 3, "nUpserted" : 0, "nModified" : 3 })在find()方法的帮助下显示集合中的所有文档-
> db.demo312.find();
这将产生以下输出-
{ "_id" : ObjectId("5e50ce16f8647eb59e56204a"), "FirstName" : "Sam" }
{ "_id" : ObjectId("5e50ce19f8647eb59e56204b"), "FirstName" : "Bob" }
{ "_id" : ObjectId("5e50ce1cf8647eb59e56204c"), "FirstName" : "Sam" }
{ "_id" : ObjectId("5e50ce20f8647eb59e56204d"), "FirstName" : "David" }
{ "_id" : ObjectId("5e50ce22f8647eb59e56204e"), "FirstName" : "Sam" }