Problem

DataFrame students +————-+——–+ | Column Name | Type | +————-+——–+ | student_id | int | | name | object | | age | int | +————-+——–+

Write a solution to select the name and age of the student with student_id = 101.

The result format is in the following example.

**Example 1:

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Input:**
+------------+---------+-----+
| student_id | name | age |
+------------+---------+-----+
| 101 | Ulysses | 13 |
| 53 | William | 10 |
| 128 | Henry | 6 |
| 3 | Henry | 11 |
+------------+---------+-----+
Output:
+---------+-----+
| name | age |
+---------+-----+
| Ulysses | 13 |
+---------+-----+
Explanation: Student Ulysses has student_id = 101, we select the name and age.

Solution

Method 1 - Simple Filtering

Intuition

We need to select the name and age of the student with a specific student_id. This is a simple filter operation.

Approach

  1. Filter the DataFrame (or table) for rows where student_id = 101.
  2. Select only the name and age columns.

Code

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SELECT name, age
FROM students
WHERE student_id = 101;
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SELECT name, age
FROM students
WHERE student_id = 101;
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# students is a pandas DataFrame
result = students.loc[students['student_id'] == 101, ['name', 'age']]

Complexity

  • ⏰ Time complexity: O(N) where N = number of students
  • 🧺 Space complexity: O(1) (output is a single row)