MongoDB Update()方法如何设置整个字段的记录？
您可以将$set运算符与一起使用update()。首先让我们创建一个包含文档的集合-
> db.workingOfUpdateMethod.insertOne({"ClientCountryName" : "AUS"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cd506fe2cba06f46efe9efa")
}
> db.workingOfUpdateMethod.insertOne({"ClientCountryName" : "AUS"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cd507022cba06f46efe9efb")
}
> db.workingOfUpdateMethod.insertOne({"ClientCountryName" : "AUS"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cd507022cba06f46efe9efc")
}
> db.workingOfUpdateMethod.insertOne({"ClientCountryName" : "AUS"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cd507032cba06f46efe9efd")
}以下是在find()方法的帮助下显示集合中所有文档的查询-
> db.workingOfUpdateMethod.find().pretty();
这将产生以下输出-
{ "_id" : ObjectId("5cd506fe2cba06f46efe9efa"), "ClientCountryName" : "AUS" }
{ "_id" : ObjectId("5cd507022cba06f46efe9efb"), "ClientCountryName" : "AUS" }
{ "_id" : ObjectId("5cd507022cba06f46efe9efc"), "ClientCountryName" : "AUS" }
{ "_id" : ObjectId("5cd507032cba06f46efe9efd"), "ClientCountryName" : "AUS" }以下是更新和设置整个字段的查询。在这里，我们正在更新字段“ClientCountryName”-
> db.workingOfUpdateMethod.update(
... {"ClientCountryName" : "AUS"},
... {$set: {"ClientCountryName" : "UK"}},
... {multi: true});
WriteResult({ "nMatched" : 4, "nUpserted" : 0, "nModified" : 4 })让我们再次检查所有文件-
> db.workingOfUpdateMethod.find().pretty();
这将产生以下输出-
{ "_id" : ObjectId("5cd506fe2cba06f46efe9efa"), "ClientCountryName" : "UK" }
{ "_id" : ObjectId("5cd507022cba06f46efe9efb"), "ClientCountryName" : "UK" }
{ "_id" : ObjectId("5cd507022cba06f46efe9efc"), "ClientCountryName" : "UK" }
{ "_id" : ObjectId("5cd507032cba06f46efe9efd"), "ClientCountryName" : "UK" }