如何使用MongoDB中的自定义字段对分页进行索引和排序？
首先让我们创建一个包含文档的集合-
> db.demo373.createIndex({"Name":1,"CountryName":1});
{
"createdCollectionAutomatically" : true,
"numIndexesBefore" : 1,
"numIndexesAfter" : 2,
"ok" : 1
}
> db.demo373.insertOne({"Name":"Chris","Age":22,"CountryName":"US"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e59ffde2ae06a1609a00aff")
}
> db.demo373.insertOne({"Name":"David","Age":21,"CountryName":"AUS"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e59ffe82ae06a1609a00b00")
}
> db.demo373.insertOne({"Name":"Bob","Age":23,"CountryName":"UK"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e59fff42ae06a1609a00b01")
}
> db.demo373.insertOne({"Name":"John","Age":21,"CountryName":"US"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e59ffff2ae06a1609a00b02")
}
> db.demo373.insertOne({"Name":"Carol","Age":23,"CountryName":"AUS"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e5a00082ae06a1609a00b03")
}在find()方法的帮助下显示集合中的所有文档-
> db.demo373.find();
这将产生以下输出-
{ "_id" : ObjectId("5e59ffde2ae06a1609a00aff"), "Name" : "Chris", "Age" : 22, "CountryName" : "US" }
{ "_id" : ObjectId("5e59ffe82ae06a1609a00b00"), "Name" : "David", "Age" : 21, "CountryName" : "AUS" }
{ "_id" : ObjectId("5e59fff42ae06a1609a00b01"), "Name" : "Bob", "Age" : 23, "CountryName" : "UK" }
{ "_id" : ObjectId("5e59ffff2ae06a1609a00b02"), "Name" : "John", "Age" : 21, "CountryName" : "US" }
{ "_id" : ObjectId("5e5a00082ae06a1609a00b03"), "Name" : "Carol", "Age" : 23, "CountryName" : "AUS" }以下是在MongoDB中使用分页实现索引和排序的查询-
> db.demo373.find().sort({"Name":1, "Age":1}).limit(4).skip(2);这将产生以下输出-
{ "_id" : ObjectId("5e59ffde2ae06a1609a00aff"), "Name" : "Chris", "Age" : 22, "CountryName" : "US" }
{ "_id" : ObjectId("5e59ffe82ae06a1609a00b00"), "Name" : "David", "Age" : 21, "CountryName" : "AUS" }
{ "_id" : ObjectId("5e59ffff2ae06a1609a00b02"), "Name" : "John", "Age" : 21, "CountryName" : "US" }