在 MongoDB 中按属性名称搜索具有该属性的任何文档？
您可以为此使用$ne运算符。让我们首先创建一个包含文档的集合-
> db.searchByPropertyName.insertOne({"FirstName":"Larry","Age":23});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cbaf7af7219729fde21ddb5")
}
> db.searchByPropertyName.insertOne({"FirstName":null,"Age":21});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cbaf7b97219729fde21ddb6")
}
> db.searchByPropertyName.insertOne({"FirstName":"John","Age":22});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cbaf7c57219729fde21ddb7")
}
> db.searchByPropertyName.insertOne({"FirstName":null,"Age":25});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cbaf7d07219729fde21ddb8")
}
> db.searchByPropertyName.insertOne({"FirstName":"David","Age":20});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cbaf7df7219729fde21ddb9")
}以下是在find()prettyprint的帮助下显示集合中所有文档的查询-
> db.searchByPropertyName.find().pretty();
这将产生以下输出-
{
"_id" : ObjectId("5cbaf7af7219729fde21ddb5"),
"FirstName" : "Larry",
"Age" : 23
}
{
"_id" : ObjectId("5cbaf7b97219729fde21ddb6"),
"FirstName" : null,
"Age" : 21
}
{
"_id" : ObjectId("5cbaf7c57219729fde21ddb7"),
"FirstName" : "John",
"Age" : 22
}
{
"_id" : ObjectId("5cbaf7d07219729fde21ddb8"),
"FirstName" : null,
"Age" : 25
}
{
"_id" : ObjectId("5cbaf7df7219729fde21ddb9"),
"FirstName" : "David",
"Age" : 20
}以下是按属性名称搜索具有该属性的任何文档的查询-
> db.searchByPropertyName.find({FirstName: { $ne : null } } ).pretty();这将产生以下输出-
{
"_id" : ObjectId("5cbaf7af7219729fde21ddb5"),
"FirstName" : "Larry",
"Age" : 23
}
{
"_id" : ObjectId("5cbaf7c57219729fde21ddb7"),
"FirstName" : "John",
"Age" : 22
}
{
"_id" : ObjectId("5cbaf7df7219729fde21ddb9"),
"FirstName" : "David",
"Age" : 20
}