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法律研究如何针对 MongoDB 文档中的哈希执行 $gt？
$gt 用于大于，其中选择值为指定值以上的字段的文档。我们首先用文档创建集合 −
> 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")
}下面是使用 find() 方法显示集合中所有文档的查询 −
> 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"
}下面是针对 MongoDB 文档中的哈希执行 $gt 的查询。在这里，我们将获得得分高于 0 的球员记录 −
> db.performQueryDemo.find({"PlayerDetails.PlayerScore":{$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" }
更新于： 2019-07-30
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