MongoDB切片数组在填充字段？
> db.demo503.insertOne({_id:1,Name:"John",Subject:["MySQL","Java","C"]});
{ "acknowledged" : true, "insertedId" : 1 }
> db.demo503.insertOne({_id:2,Name:"David",Subject:["MongoDB","C++","Python"]});
{ "acknowledged" : true, "insertedId" : 2 }在find()方法的帮助下显示集合中的所有文档-
> db.demo503.find().pretty();
这将产生以下输出-
{ "_id" : 1, "Name" : "John", "Subject" : [ "MySQL", "Java", "C" ] }
{
"_id" : 2,
"Name" : "David",
"Subject" : [
"MongoDB",
"C++",
"Python"
]
}以下是对填充字段中的切片数组的查询-
> db.demo503.find({_id:2}, { 'Subject': { $slice: -1 }});这将产生以下输出-
{ "_id" : 2, "Name" : "David", "Subject" : [ "Python" ] }热门推荐
10 哥哥考大学祝福语简短
11 杨奕老师祝福语简短
12 圣诞祝福语简短文字
13 幼儿狗年祝福语大全简短
14 法考面试祝福语简短
15 冬至婆婆的祝福语简短
16 发小结婚简短祝福语
17 给宝贝开学祝福语简短
18 理科元旦祝福语大全简短