MongoDB 如何在集合中对文档进行排序?
mongodbdatabasebig data analytics
MongoDB 使用 $natural 运算符对集合中的文档进行排序。它会按 find() 获取文档时的原样存储文档。默认顺序为 $natural。现在让我们看看语法 −
db.yourCollectionName.find().sort({ "$natural": 1 });
为了理解上述语法，让我们创建一个包含文档的集合。创建包含文档的集合的查询如下 −
> db.orderDocsDemo.insertOne({"UserScore":87});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c9531a316f542d757e2b44b")
}
> db.orderDocsDemo.insertOne({"UserScore":98});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c9531a816f542d757e2b44c")
}
> db.orderDocsDemo.insertOne({"UserScore":99});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c9531b216f542d757e2b44d")
}
> db.orderDocsDemo.insertOne({"UserScore":67});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c9531b716f542d757e2b44e")
}
> db.orderDocsDemo.insertOne({"UserScore":78});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c9531bd16f542d757e2b44f")
}
> db.orderDocsDemo.insertOne({"UserScore":91});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c9531c416f542d757e2b450")
}
> db.orderDocsDemo.insertOne({"UserScore":86});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c9531c816f542d757e2b451")
}
使用 find() 方法显示集合中的所有文档。查询如下 −
> db.orderDocsDemo.find();
以下是输出 −
{ "_id" : ObjectId("5c9531a316f542d757e2b44b"), "UserScore" : 87 }
{ "_id" : ObjectId("5c9531a816f542d757e2b44c"), "UserScore" : 98 }
{ "_id" : ObjectId("5c9531b216f542d757e2b44d"), "UserScore" : 99 }
{ "_id" : ObjectId("5c9531b716f542d757e2b44e"), "UserScore" : 67 }
{ "_id" : ObjectId("5c9531bd16f542d757e2b44f"), "UserScore" : 78 }
{ "_id" : ObjectId("5c9531c416f542d757e2b450"), "UserScore" : 91 }
{ "_id" : ObjectId("5c9531c816f542d757e2b451"), "UserScore" : 86 }
这是对一个集合中的文档进行排序的查询 −
> db.orderDocsDemo.find().sort({ "$natural": 1 });
以下是输出 −
{ "_id" : ObjectId("5c9531a316f542d757e2b44b"), "UserScore" : 87 }
{ "_id" : ObjectId("5c9531a816f542d757e2b44c"), "UserScore" : 98 }
{ "_id" : ObjectId("5c9531b216f542d757e2b44d"), "UserScore" : 99 }
{ "_id" : ObjectId("5c9531b716f542d757e2b44e"), "UserScore" : 67 }
{ "_id" : ObjectId("5c9531bd16f542d757e2b44f"), "UserScore" : 78 }
{ "_id" : ObjectId("5c9531c416f542d757e2b450"), "UserScore" : 91 }
{ "_id" : ObjectId("5c9531c816f542d757e2b451"), "UserScore" : 86 }
查看上面的示例输出，我们以插入的方式获取了相同的文档。
为了获取排序后的文档，请使用以下查询 −
> db.orderDocsDemo.find().sort({ "UserScore": 1 });
以下是输出 −
{ "_id" : ObjectId("5c9531b716f542d757e2b44e"), "UserScore" : 67 }
{ "_id" : ObjectId("5c9531bd16f542d757e2b44f"), "UserScore" : 78 }
{ "_id" : ObjectId("5c9531c816f542d757e2b451"), "UserScore" : 86 }
{ "_id" : ObjectId("5c9531a316f542d757e2b44b"), "UserScore" : 87 }
{ "_id" : ObjectId("5c9531c416f542d757e2b450"), "UserScore" : 91 }
{ "_id" : ObjectId("5c9531a816f542d757e2b44c"), "UserScore" : 98 }
{ "_id" : ObjectId("5c9531b216f542d757e2b44d"), "UserScore" : 99 }
