Find all employees in the `"Engineering"` department.

Problem Statement

<p>Find all <code>employees</code> in the <code>"Engineering"</code> department.</p>

Examples

Input: employees collection: +-----+---------+-------------+--------+ | _id | name | dept | salary | +-----+---------+-------------+--------+ | 1 | Alice | Engineering | 90000 | | 2 | Bob | Marketing | 60000 | | 3 | Charlie | Engineering | 85000 | +-----+---------+-------------+--------+

Output: +-----+---------+-------------+--------+ | _id | name | dept | salary | +-----+---------+-------------+--------+ | 1 | Alice | Engineering | 90000 | | 3 | Charlie | Engineering | 85000 | +-----+---------+-------------+--------+

Explanation: The query retrieves all documents from the collection that satisfy the specified filter criteria.

Complexity

Time Complexity: -

Space Complexity: -

Hints

💡 Hint 1: Use db.<collection>.find(<filter>) to query the documents in the collection. 💡 Hint 2: Pass an empty object {} to retrieve all documents, or specify key-value pairs for exact matching. 💡 Hint 3: Chain .toArray() to resolve the MongoDB cursor into a JavaScript array: return db.<collection>.find(...).toArray();

Editorial & Approach

Problem Overview & Intuition

To solve "Equality Filter", we query the MongoDB document store. The goal is to find all employees in the `"engineering"` department. Using a targeted find query, the database engine filters and structures the BSON documents efficiently.

Step-by-Step Approach

Identify Target Collection: Access the collection through the db instance.
Construct Query / Pipeline: Build the query filter with appropriate comparison operators.
Resolve Cursor: Invoke .toArray() to transform the query cursor into the required array of documents.

Optimal Implementation (MongoDB)

function solve(db) {
  return db.employees.find({ dept: "Engineering" }).toArray();
}

Complexity Analysis

Time Complexity O(N) collection scan (O(log N) if index is present on filtered fields).

Space Complexity O(K) where K is the number of returned documents in memory.

Key Considerations & Edge Cases

Empty Collections: If no documents match, the query cleanly returns an empty array [].
Missing / NULL Fields: Missing fields in documents are handled safely without throwing runtime exceptions.
Type Coercion: BSON types (ObjectId, Numbers, Strings) are compared strictly according to MongoDB specifications.

Equality Filter

Easy

Find all employees in the "Engineering" department.

Example Scenarios

1Example 1

Input:

employees collection

_id	name	dept	salary
1	Alice	Engineering	90000
2	Bob	Marketing	60000
3	Charlie	Engineering	85000

Output:

_id	name	dept	salary
1	Alice	Engineering	90000
3	Charlie	Engineering	85000

Explanation:

The query retrieves all documents from the collection that satisfy the specified filter criteria.

MongoDB Editor

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Query Results (JSON)

Run your MongoDB code to see results here.