如何在MongoDB中排序？
要在MongoDB中排序，可以使用sort()方法。
情况1-升序排列。语法如下-
db.yourCollectionName.find().sort({yourField:1});情况2-降序排列。语法如下-
db.yourCollectionName.find().sort({yourField:-1});为了理解这个概念，让我们用文档创建一个集合。使用文档创建集合的查询如下-
> db.sortingDemo.insertOne({"Value":100});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c8f8e2ed3c9d04998abf006")
}
> db.sortingDemo.insertOne({"Value":1});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c8f8e31d3c9d04998abf007")
}
> db.sortingDemo.insertOne({"Value":150});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c8f8e34d3c9d04998abf008")
}
> db.sortingDemo.insertOne({"Value":250});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c8f8e37d3c9d04998abf009")
}
> db.sortingDemo.insertOne({"Value":5});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c8f8e3bd3c9d04998abf00a")
}
> db.sortingDemo.insertOne({"Value":199});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c8f8e3ed3c9d04998abf00b")
}
> db.sortingDemo.insertOne({"Value":243});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c8f8e44d3c9d04998abf00c")
}
> db.sortingDemo.insertOne({"Value":290});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c8f8e48d3c9d04998abf00d")
}在find()method的帮助下显示集合中的所有文档。查询如下-
> db.sortingDemo.find().pretty();
以下是输出-
{ "_id" : ObjectId("5c8f8e2ed3c9d04998abf006"), "Value" : 100 }
{ "_id" : ObjectId("5c8f8e31d3c9d04998abf007"), "Value" : 1 }
{ "_id" : ObjectId("5c8f8e34d3c9d04998abf008"), "Value" : 150 }
{ "_id" : ObjectId("5c8f8e37d3c9d04998abf009"), "Value" : 250 }
{ "_id" : ObjectId("5c8f8e3bd3c9d04998abf00a"), "Value" : 5 }
{ "_id" : ObjectId("5c8f8e3ed3c9d04998abf00b"), "Value" : 199 }
{ "_id" : ObjectId("5c8f8e44d3c9d04998abf00c"), "Value" : 243 }
{ "_id" : ObjectId("5c8f8e48d3c9d04998abf00d"), "Value" : 290 }情况1-这是按升序获取结果的查询
> db.sortingDemo.find().sort({Value:1});以下是输出-
{ "_id" : ObjectId("5c8f8e31d3c9d04998abf007"), "Value" : 1 }
{ "_id" : ObjectId("5c8f8e3bd3c9d04998abf00a"), "Value" : 5 }
{ "_id" : ObjectId("5c8f8e2ed3c9d04998abf006"), "Value" : 100 }
{ "_id" : ObjectId("5c8f8e34d3c9d04998abf008"), "Value" : 150 }
{ "_id" : ObjectId("5c8f8e3ed3c9d04998abf00b"), "Value" : 199 }
{ "_id" : ObjectId("5c8f8e44d3c9d04998abf00c"), "Value" : 243 }
{ "_id" : ObjectId("5c8f8e37d3c9d04998abf009"), "Value" : 250 }
{ "_id" : ObjectId("5c8f8e48d3c9d04998abf00d"), "Value" : 290 }情况2-这是按降序获取结果的查询。查询如下-
> db.sortingDemo.find().sort({Value:-1});以下是输出-
{ "_id" : ObjectId("5c8f8e48d3c9d04998abf00d"), "Value" : 290 }
{ "_id" : ObjectId("5c8f8e37d3c9d04998abf009"), "Value" : 250 }
{ "_id" : ObjectId("5c8f8e44d3c9d04998abf00c"), "Value" : 243 }
{ "_id" : ObjectId("5c8f8e3ed3c9d04998abf00b"), "Value" : 199 }
{ "_id" : ObjectId("5c8f8e34d3c9d04998abf008"), "Value" : 150 }
{ "_id" : ObjectId("5c8f8e2ed3c9d04998abf006"), "Value" : 100 }
{ "_id" : ObjectId("5c8f8e3bd3c9d04998abf00a"), "Value" : 5 }
{ "_id" : ObjectId("5c8f8e31d3c9d04998abf007"), "Value" : 1 }