M101J: MongoDB for Java Developers - Homework 2.1

Step 1:

Download Grades.js

Step 2:

Load grade.js using mongo import

mongoimport -d students -c grades < grades.js

Step 3:

use students

db.grades.count() 

Count Should be 800

Step 4:

Question? 

Find all exam scores greater than or equal to 65 

and sort those scores from lowest to highest. 

Understanding Question:

1) it says that we need to find score greater than or equal to 65.

so we will use $gte so our query criteria will be 

{"score":{"$gte":65}}

2) then it says to sort the score from lowest to highest.

for this we will use sort filter  and it is query criteria will be 

{"score":1}.

so our query will be 

 db.grades.find({"score":{"$gte":65.0}}).sort({"score":1})

Note: to sort in ascending order use  {"score":1}

to sort in descending order use  {"score":-1}

first document in the result you will find the answer 

3) optional : you can limit the number of rows, you will get only 1 document

by executing final query. so that you dont have to scroll. 

Final Query: 

 db.grades.find({"score":{"$gte":65.0}}).sort({"score":1}).limit(1).pretty();