如何使用 skip 和 limit 命令显示不同顺序的 MongoDB 记录?
mongodbdatabasebig data analytics更新于 2026/1/16 14:22:17
您可以使用聚合框架并使用 $sort、$skip 和 $limit 命令显示不同顺序的记录，并设置限制。首先，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")
}
以下是使用 find() 方法显示集合中的所有文档的查询 −
> 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" }
这是使用跳过和限制来显示清晰排序记录的查询 −
> 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" }
