MongoDB查询以数组形式仅返回特定字段（电话号码）？
让我们创建一个包含文档的集合-
> db.demo166.insertOne({"details" : { "UserName" : "Chris", "UserAge":29, "PhoneDetails" : { "PhoneNumber" : "98646463533" } } });
{
"acknowledged" : true,
"insertedId" : ObjectId("5e368b159e4f06af551997cf")
}
> db.demo166.insertOne({"details" : { "UserName" : "David", "UserAge":21, "PhoneDetails" : { "PhoneNumber" : "87664534654" } } });
{
"acknowledged" : true,
"insertedId" : ObjectId("5e368b159e4f06af551997d0")
}在find()方法的帮助下显示集合中的所有文档-
> db.demo166.find();
这将产生以下输出-
{ "_id" : ObjectId("5e368b159e4f06af551997cf"), "details" : { "UserName" : "Chris", "UserAge" : 29, "PhoneDetails" : { "PhoneNumber" : "98646463533" } } }
{ "_id" : ObjectId("5e368b159e4f06af551997d0"), "details" : { "UserName" : "David", "UserAge" : 21, "PhoneDetails" : { "PhoneNumber" : "87664534654" } } }以下是仅以数组形式返回特定字段（号码）的查询-
> db.demo166.distinct("details.PhoneDetails.PhoneNumber");这将产生以下输出-
[ "98646463533", "87664534654" ]