mongodb

This project involves designing and querying a MongoDB database for a Zen class program. The database includes collections for users, attendance, tasks, topics, company_drives, and mentors. Below is a summary of the tasks performed and queries used.

Collections

1. Attendance

Tracks user attendance with fields:

user_id: ID of the user.
date: Attendance date (ISODate format).
attendance: Status ("Present" or "Absent").

2. Tasks

Tracks tasks assigned to users:

topic_id: ID of the related topic.
title: Task title.
due_date: Task due date.
status: Task completion status ("Pending" or "Completed").

Tasks Performed

Query Objectives

Find all topics and tasks taught in October.
Retrieve company drives conducted between 15-Oct-2020 and 31-Oct-2020.
List company drives along with students who appeared for placements.
Count the number of problems solved by users in codekata.
Retrieve mentors with a mentee count greater than 15.
Identify users who were absent and didn’t submit tasks between 15-Oct-2020 and 31-Oct-2020.

Key Query Example: Attendance and Tasks Analysis

db.attendance.aggregate([
  {
    $match: {
      date: {
        $gte: ISODate("2020-10-15T00:00:00Z"),
        $lte: ISODate("2020-10-31T00:00:00Z")
      },
      attendance: "Absent"
    }
  },
  {
    $lookup: {
      from: "tasks",
      localField: "user_id",
      foreignField: "user_id",
      as: "tasks"
    }
  },
  {
    $unwind: "$tasks"
  },
  {
    $match: {
      "tasks.status": "Pending"
    }
  },
  {
    $project: {
      user_id: 1,
      date: 1,
      "tasks.title": 1,
      "tasks.status": 1
    }
  }
]);

Results

Topics and Tasks for October: Retrieved based on the date field.
Company Drives in Date Range: Filtered using $gte and $lte.
Absent Users with Pending Tasks: Identified using $lookup, $unwind, and $match.

vaibhavapriya/mongodb