如何在MongoDB中删除文档中的特定数据？
您可以使用$unset。首先让我们创建一个包含文档的集合-
> db.demo20.insertOne(
... {
...
... "ListOfEmployee" : [
... {
... "EmployeeName1" : "John"
... },
... {
... "EmployeeName2" : "Carol"
... }
... ],
... "EmployeeName2" : []
... }
... );
{
"acknowledged" : true,
"insertedId" : ObjectId("5e138c3555d0fc6657d21f12")
}以下是在find()方法的帮助下显示集合中所有文档的查询-
> db.demo20.find();
这将产生以下输出-
{ "_id" : ObjectId("5e138c3555d0fc6657d21f12"), "ListOfEmployee" : [ { "EmployeeName1" : "John" }, { "EmployeeName2" : "Carol" } ], "EmployeeName2" : [ ] }以下是删除文档中特定数据的查询-
> db.demo20.update({ "EmployeeName2": { "$exists": 1 }},{ "$unset": { "EmployeeName2": "" } });
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })以下是在find()方法的帮助下显示集合中所有文档的查询-
> db.demo20.find();
这将产生以下输出-
{ "_id" : ObjectId("5e138c3555d0fc6657d21f12"), "ListOfEmployee" : [ { "EmployeeName1" : "John" }, { "EmployeeName2" : "Carol" } ] }