如何根据名称列表获取 MongoDB 查询结果中的标签数量?
mongodbdatabasebig data analytics
您可以使用 $in 运算符。首先，我们创建一个包含文档的集合 −
> db.tagCountDemo.insertOne({"ListOfNames":["John","Sam","Carol"]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cd64b387924bb85b3f48944")
}
> db.tagCountDemo.insertOne({"ListOfNames":["Bob","David","John"]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cd64b4b7924bb85b3f48945")
}
> db.tagCountDemo.insertOne({"ListOfNames":["Mike","Robert","Chris"]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cd64b5d7924bb85b3f48946")
}
> db.tagCountDemo.insertOne({"ListOfNames":["James","Carol","Jace"]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cd64b717924bb85b3f48947")
}
以下是使用 find() 方法显示集合中的所有文档的查询 −
> db.tagCountDemo.find().pretty();
这将产生以下输出 −
{
"_id" : ObjectId("5cd64b387924bb85b3f48944"),
"ListOfNames" : [
"John",
"Sam",
"Carol"
]
}
{
"_id" : ObjectId("5cd64b4b7924bb85b3f48945"),
"ListOfNames" : [
"Bob",
"David",
"John"
]
}
{
"_id" : ObjectId("5cd64b5d7924bb85b3f48946"),
"ListOfNames" : [
"Mike",
"Robert",
"Chris"
]
}
{
"_id" : ObjectId("5cd64b717924bb85b3f48947"),
"ListOfNames" : [
"James",
"Carol",
"Jace"
]
}
以下是在 MongoDB 中获取标签计数的查询
> db.tagCountDemo.find({"ListOfNames":{$in:['John','Carol']}});
这将产生以下输出 −
{ "_id" : ObjectId("5cd64b387924bb85b3f48944"), "ListOfNames" : [ "John", "Sam", "Carol" ] }
{ "_id" : ObjectId("5cd64b4b7924bb85b3f48945"), "ListOfNames" : [ "Bob", "David", "John" ] }
{ "_id" : ObjectId("5cd64b717924bb85b3f48947"), "ListOfNames" : [ "James", "Carol", "Jace" ] }
