如何在 MongoDB 集合中查找最早/最新的帖子?
mongodbdatabasebig data analytics更新于 2026/1/18 1:52:17
要在 MongoDB 集合中查找最早/最新的帖子，可以使用 sort()。假设您有一个包含字段"UserPostDate"的文档，您需要获取最早和最新的帖子。为此，我们首先创建一个包含文档的集合。
>db.getOldestAndYoungestPostDemo.insertOne({"UserId":"Larry@123","UserName":"Larry","UserPostDate":new ISODate('2019-03-27 12:00:00')});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c9a700f15e86fd1496b38ab")
}
>db.getOldestAndYoungestPostDemo.insertOne({"UserId":"Sam@897","UserName":"Sam","UserPostDate":new ISODate('2012-06-17 11:40:30')});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c9a703815e86fd1496b38ac")
}
>db.getOldestAndYoungestPostDemo.insertOne({"UserId":"David@777","UserName":"David","UserPostDate":new ISODate('2018-01-31 10:45:35')});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c9a705e15e86fd1496b38ad")
}
>db.getOldestAndYoungestPostDemo.insertOne({"UserId":"Chris@909","UserName":"Chris","UserPostDate":new ISODate('2017-04-14 04:12:04')});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c9a708915e86fd1496b38ae")
}
以下是借助 find() 方法显示集合中的所有文档的查询
> db.getOldestAndYoungestPostDemo.find().pretty();
这将产生以下输出 −
{
"_id" : ObjectId("5c9a700f15e86fd1496b38ab"),
"UserId" : "Larry@123",
"UserName" : "Larry",
"UserPostDate" : ISODate("2019-03-27T12:00:00Z")
}
{
"_id" : ObjectId("5c9a703815e86fd1496b38ac"),
"UserId" : "Sam@897",
"UserName" : "Sam",
"UserPostDate" : ISODate("2012-06-17T11:40:30Z")
}
{
"_id" : ObjectId("5c9a705e15e86fd1496b38ad"),
"UserId" : "David@777",
"UserName" : "David",
"UserPostDate" : ISODate("2018-01-31T10:45:35Z")
}
{
"_id" : ObjectId("5c9a708915e86fd1496b38ae"),
"UserId" : "Chris@909",
"UserName" : "Chris",
"UserPostDate" : ISODate("2017-04-14T04:12:04Z")
}
以下是在 MongoDB 集合中查找最旧帖子的查询
> db.getOldestAndYoungestPostDemo.find().sort({ "UserPostDate" : 1 }).limit(1);
这将产生以下输出 −
{ "_id" : ObjectId("5c9a703815e86fd1496b38ac"), "UserId" : "Sam@897", "UserName" : "Sam", "UserPostDate" : ISODate("2012-06-17T11:40:30Z") }
以下查询用于查找 MongoDB 集合中最年轻(最近)的帖子
> db.getOldestAndYoungestPostDemo.find().sort({ "UserPostDate" : -1 }).limit(1);
这将产生以下输出 −
{ "_id" : ObjectId("5c9a700f15e86fd1496b38ab"), "UserId" : "Larry@123", "UserName" : "Larry", "UserPostDate" : ISODate("2019-03-27T12:00:00Z") }
