仅更新MongoDB中的特定字段？
要仅更新特定字段，可以使用$set运算符。首先让我们创建一个包含文档的集合
>db.updateOnlySpecificFieldDemo.insertOne({"EmployeeName":"John","EmployeeCountryName":"UK"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c9ea849d628fa4220163b72")
}
>db.updateOnlySpecificFieldDemo.insertOne({"EmployeeName":"Larry","EmployeeCountryName":"US"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c9ea853d628fa4220163b73")
}
>db.updateOnlySpecificFieldDemo.insertOne({"EmployeeName":"David","EmployeeCountryName":"AUS"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c9ea85bd628fa4220163b74")
}以下是在find()方法的帮助下显示集合中所有文档的查询
> db.updateOnlySpecificFieldDemo.find().pretty();
这将产生以下输出
{
"_id" : ObjectId("5c9ea849d628fa4220163b72"),
"EmployeeName" : "John",
"EmployeeCountryName" : "UK"
}
{
"_id" : ObjectId("5c9ea853d628fa4220163b73"),
"EmployeeName" : "Larry",
"EmployeeCountryName" : "US"
}
{
"_id" : ObjectId("5c9ea85bd628fa4220163b74"),
"EmployeeName" : "David",
"EmployeeCountryName" : "AUS"
}以下是仅更新特定字段的查询
> db.updateOnlySpecificFieldDemo.update({_id:ObjectId("5c9ea849d628fa4220163b72")},
... {$set: {"EmployeeName":"Robert"}});
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })现在您可以检查字段“EmployeeName”：“John”是否已更新为值“Robert”。以下是查询
> db.updateOnlySpecificFieldDemo.find().pretty();
这将产生以下输出
{
"_id" : ObjectId("5c9ea849d628fa4220163b72"),
"EmployeeName" : "Robert",
"EmployeeCountryName" : "UK"
}
{
"_id" : ObjectId("5c9ea853d628fa4220163b73"),
"EmployeeName" : "Larry",
"EmployeeCountryName" : "US"
}
{
"_id" : ObjectId("5c9ea85bd628fa4220163b74"),
"EmployeeName" : "David",
"EmployeeCountryName" : "AUS"
}查看上面的示例输出，“EmployeeName”已成功更新。
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