//

use tinker

// collection: test1
db.test1.insertOne(
   {
      "StudentId" :1,
      "StudentName" : "Joseph Connor"
   }
)

doc = {
      "StudentId" :1,
      "StudentName" : "Joseph Connor"
   }
doc
db.test1.insertOne(doc)

db.test1.find()

if (db.test1.find(doc).count() == 0) { db.test1.insertOne(doc) }


doc2 = {
      "StudentId" :1,
      "StudentName" : "Sarah Connor"
   }
doc2
if (db.test1.find(doc2).count() == 0) { db.test1.insertOne(doc2) }


show dbs
db.dropDatabase()
show dbs

// remove tinker
use tinker
db.test1.find()
doc = {
      "StudentId" :1,
      "StudentName" : "Joseph Connor"
}
doc
if (db.test1.find(doc).count() == 0) { db.test1.insertOne(doc) }
db.test1.find()
if (db.test1.find(doc).count() == 0) { db.test1.insertOne(doc) }
db.test1.find()


// create index

// db.collection.createIndex(keys, options, commitQuorum)
//keys: { "StudentId": 1 }; 1: true
// options:  { unique: true }
db.test1.createIndex( { "StudentId": 1 }, { unique: true } )
doc = {
      "StudentId" :1,
      "StudentName" : "Joseph Connor"
}
doc
db.test1.insertOne(doc)
db.test1.insertOne(doc)

doc2 = {
      "StudentId" :1,
      "StudentName" : "Sarah Smith"
   }
doc2
db.test1.insertOne(doc2)

doc3 = {
      "StudentId" :7,
      "StudentName" : "Linda Johnson"
   }
doc3
db.test1.insertOne(doc3)

db.test1.insertMany([
   {   "StudentId" :2,
      "GPA": 3.72
   },
   {   "StudentId" :3,
      "GPA": 1.69,
      "HairColor": "white"
   },
   {
      "BCAssetId": "78c22fc6-5dec-11ec-bf63-0242ac130002",
      "BCAssetType": "BCAssetTypeMetadata",
      "BCAssetName": "BCAssetTypeMetadata: MBSEModel",
      "ForBCAssetType": "MBSEModel",
      "Version": {
         "Version": "1.0",
         "Subversion": null,
         "StartTime": "2019-01-13T07:23:13+06:00"
      }
   }
])
db.test1.find()
// no arguments. 

// db.collection.find( <query>, <projection>, <options> )

db.student.find()

db.student.find({},
   { "_id": 0 }  
)
// <query>: {}
// <projection>: { "_id": 0 }  0: false

db.student.find({},
   { "_id": false }  
)

// Show all information of students majoring in 'CINF'.
// <query>: {"major": "CINF"}


db.student.find({"major": "CINF"},
    { "_id": 0 }
)

db.student.find({"mjor": "CINF"},
    { "_id": 0 }
)

db.student.find({"major": "cinf"},
    { "_id": 0 }
)

// Show all student names. Return an array of student objects.
db.student.find({},
   { "fname": 1, "lname":1, "_id": 0 }  
)

db.student.find({},
   { "fname": 1, "lname":1 }  
)

/*
Show all student names in this format:
student #0: Tony Hawk
student #1: Mary Hawk
student #2: David Hawk
student #3: Catherine Lim
student #4: Larry Johnson
student #5: Linda Johnson
student #6: Lillian Johnson
student #7: Ben Zico
student #8: Bill Ching
student #9: Linda King
Solution:

*/

result = db.student.find({},
   { "fname": 1, "lname":1, "_id": 0 }  
).toArray()

// May not always work as toArray() returns a promise,
// which may not be ready for use.
result.forEach((x,i) => console.log('student #' + String(i) + ': ' + x["fname"] + ' ' + x["lname"]))

result.forEach((x,i) => console.log('student #' + String(i+1) + ': ' + x["fname"] + ' ' + x["lname"]))