如何查询MongoDB中的所有项目？
要查询所有项目，请使用find()。首先让我们创建一个包含文档的集合-
> db.queryAllItemsDemo.insertOne({"StudentDetails":{"StudentName":"John","StudentSubject":["MongoDB","MySQL"],"StudentSubjectPrice":[4000,6000]},"OtherDetails":{"UserAge":29,"UserCountryName":"US"}});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cef74ecef71edecf6a1f69f")
}在find()方法的帮助下显示集合中的所有文档-
> db.queryAllItemsDemo.find().pretty();
这将产生以下输出-
{
"_id" : ObjectId("5cef74ecef71edecf6a1f69f"),
"StudentDetails" : {
"StudentName" : "John",
"StudentSubject" : [
"MongoDB",
"MySQL"
],
"StudentSubjectPrice" : [
4000,
6000
]
},
"OtherDetails" : {
"UserAge" : 29,
"UserCountryName" : "US"
}
}以下是如何查询MongoDB中的所有项目-
> db.queryAllItemsDemo.find({},{StudentDetails: 1}).pretty();这将产生以下输出-
{
"_id" : ObjectId("5cef74ecef71edecf6a1f69f"),
"StudentDetails" : {
"StudentName" : "John",
"StudentSubject" : [
"MongoDB",
"MySQL"
],
"StudentSubjectPrice" : [
4000,
6000
]
}
}