// 2024_4_17.js

// Mongosh
mongosh.exe

// Set up toyu DB in Mongo.
mongorestore --archive="toyu-db.gz" --gzip --nsFrom='toyu.*' --nsTo='toyu.*'

// [1] Show all students.
use toyu

db.student.find()

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

// Getting rid of _id:
// query: {}
// projection: { "_id": 0 } 
db.student.find({},
   { "_id": 0 }  
)

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

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

// Show all information of students majoring in 'CINF'.
// query: {"major": "CINF"}
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({"major": "CINF"},
   { "fname": 1, "lname":1, "major": 1, "minor": 1, "_id": 0 }  
)

[4] 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"]))

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


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