如何在MongoDB中的子文档上触发查找查询？
> db.demo537.insertOne({"details":{"SubjectName":"MongoDB"}});{
"acknowledged" : true,
"insertedId" : ObjectId("5e8c8a10ef4dcbee04fbbc05")
}
> db.demo537.insertOne({"details":{"SubjectName":"MySQL"}});{
"acknowledged" : true,
"insertedId" : ObjectId("5e8c8a4bef4dcbee04fbbc06")
}
> db.demo537.insertOne({"details":{"SubjectName":"Java"}});{
"acknowledged" : true,
"insertedId" : ObjectId("5e8c8a51ef4dcbee04fbbc07")
}在find()方法的帮助下显示集合中的所有文档-
> db.demo537.find();
这将产生以下输出-
{ "_id" : ObjectId("5e8c8a10ef4dcbee04fbbc05"), "details" : { "SubjectName" : "MongoDB" } }
{ "_id" : ObjectId("5e8c8a4bef4dcbee04fbbc06"), "details" : { "SubjectName" : "MySQL" } }
{ "_id" : ObjectId("5e8c8a51ef4dcbee04fbbc07"), "details" : { "SubjectName" : "Java" } }以下是对MongoDB中的子文档进行查询的查询-
> db.demo537.count({'details.SubjectName': 'MongoDB'})这将产生以下输出-
1