MongoDB查询仅对数组的一个元素进行切片
> db.demo579.insertOne(
... {
... "_id" : 101,
... "details" : { "FirstName" : "John" },
... "Marks" : [ 56,78,90,34,45,74 ]
... }
... );
{ "acknowledged" : true, "insertedId" : 101 }在find()方法的帮助下显示集合中的所有文档-
> db.demo579.find().pretty();
这将产生以下输出-
{
"_id" : 101,
"details" : {
"FirstName" : "John"
},
"Marks" : [
56,
78,
90,
34,
45,
74
]
}以下是仅对数组元素进行切片的查询-
> db.demo579.find({},{Marks : {$slice : 1} ,"details":0,"_id":0})这将产生以下输出-
{ "Marks" : [ 56 ] }