显示带有跳过和限制的明显排序的MongoDB记录？
您可以使用聚合框架，并使用$sort，$skip和$limit通过skip显示不同顺序的记录，并设置限制。首先让我们创建一个包含文档的集合
> db.orderedDistinctDemo.insertOne({"Name":"John"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5ccfb8e0140b992277dae0e9")
}
> db.orderedDistinctDemo.insertOne({"Name":"Larry"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5ccfb8e5140b992277dae0ea")
}
> db.orderedDistinctDemo.insertOne({"Name":"Larry"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5ccfb8e7140b992277dae0eb")
}
> db.orderedDistinctDemo.insertOne({"Name":"Sam"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5ccfb8ea140b992277dae0ec")
}
> db.orderedDistinctDemo.insertOne({"Name":"John"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5ccfb8ee140b992277dae0ed")
}
> db.orderedDistinctDemo.insertOne({"Name":"Carol"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5ccfb8f2140b992277dae0ee")
}
> db.orderedDistinctDemo.insertOne({"Name":"David"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5ccfb8f6140b992277dae0ef")
}
> db.orderedDistinctDemo.insertOne({"Name":"Carol"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5ccfb8f9140b992277dae0f0")
}以下是在find()方法的帮助下显示集合中所有文档的查询-
> db.orderedDistinctDemo.find().pretty();
这将产生以下输出-
{ "_id" : ObjectId("5ccfb8e0140b992277dae0e9"), "Name" : "John" }
{ "_id" : ObjectId("5ccfb8e5140b992277dae0ea"), "Name" : "Larry" }
{ "_id" : ObjectId("5ccfb8e7140b992277dae0eb"), "Name" : "Larry" }
{ "_id" : ObjectId("5ccfb8ea140b992277dae0ec"), "Name" : "Sam" }
{ "_id" : ObjectId("5ccfb8ee140b992277dae0ed"), "Name" : "John" }
{ "_id" : ObjectId("5ccfb8f2140b992277dae0ee"), "Name" : "Carol" }
{ "_id" : ObjectId("5ccfb8f6140b992277dae0ef"), "Name" : "David" }
{ "_id" : ObjectId("5ccfb8f9140b992277dae0f0"), "Name" : "Carol" }这是查询来显示具有跳跃和限制的明显排序的记录-
> db.orderedDistinctDemo.aggregate(
... { $group : { _id : "$Name" }},
... { $sort : { _id: 1 }},
... { $skip : 3 },
... { $limit : 8 }
... );这将产生以下输出-
{ "_id" : "Larry" }
{ "_id" : "Sam" }