如何在 MongoDB 文档中对哈希值执行 $gt 操作?
mongodbdatabasebig data analytics
$gt 用于选择大于值，即选择字段值大于指定值的文档。我们首先创建一个包含所有文档的集合。
> db.performQueryDemo.insertOne({"PlayerDetails":{"PlayerScore":1000,"PlayerLevel":2},"PlayerName":"Chris"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cd7eba41a844af18acdffa9")
}
> db.performQueryDemo.insertOne({"PlayerDetails":{"PlayerScore":0,"PlayerLevel":1},"PlayerName":"Robert"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cd7ebbb1a844af18acdffaa")
}
> db.performQueryDemo.insertOne({"PlayerDetails":{"PlayerScore":-10,"PlayerLevel":0},"PlayerName":"Larry"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cd7ebd41a844af18acdffab")
}
> db.performQueryDemo.insertOne({"PlayerDetails":{"PlayerScore":1,"PlayerLevel":1},"PlayerName":"David"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cd7ebe31a844af18acdffac")
}
以下是使用 find() 方法显示集合中的所有文档的查询 −
> db.performQueryDemo.find().pretty();
这将产生以下输出 −
{
"_id" : ObjectId("5cd7eba41a844af18acdffa9"),
"PlayerDetails" : {
"PlayerScore" : 1000,
"PlayerLevel" : 2
},
"PlayerName" : "Chris"
}
{
"_id" : ObjectId("5cd7ebbb1a844af18acdffaa"),
"PlayerDetails" : {
"PlayerScore" : 0,
"PlayerLevel" : 1
},
"PlayerName" : "Robert"
}
{
"_id" : ObjectId("5cd7ebd41a844af18acdffab"),
"PlayerDetails" : {
"PlayerScore" : -10,
"PlayerLevel" : 0
},
"PlayerName" : "Larry"
}
{
"_id" : ObjectId("5cd7ebe31a844af18acdffac"),
"PlayerDetails" : {
"PlayerScore" : 1,
"PlayerLevel" : 1
},
"PlayerName" : "David"
}
以下查询用于对 MongoDB 文档中的哈希值执行 $gt 操作。这里，我们将获取得分大于 0 的玩家记录。
> db.performQueryDemo.find({"PlayerDetails.PlayerScore":{$gt:0}});
这将产生以下输出 −
{ "_id" : ObjectId("5cd7eba41a844af18acdffa9"), "PlayerDetails" : { "PlayerScore" : 1000, "PlayerLevel" : 2 }, "PlayerName" : "Chris" }
{ "_id" : ObjectId("5cd7ebe31a844af18acdffac"), "PlayerDetails" : { "PlayerScore" : 1, "PlayerLevel" : 1 }, "PlayerName" : "David" }
