🚀 My Dev Journey Begins + Swapping Genders in SQL (LeetCode Problem)

Hi everyone! 👋
I'm starting this dev journal to track my weekly progress in software development and problem solving. I’m currently focusing on strengthening my foundations in Data Structures, Algorithms, and Database SQL through platforms like LeetCode.

This journal is not only to document what I solve, but also how I think, improve, and learn — and hopefully, someone else finds it useful too!

First Problem: Swapping 'm' and 'f' in SQL

This week's problem was from LeetCode:

Goal: Swap all 'm' and 'f' values in the sex column using a single SQL update statement, without using any intermediate tables or SELECT queries.

Here's the table:

Table: Salary

+-------------+----------+
| Column Name | Type     |
+-------------+----------+
| id          | int      |
| name        | varchar  |
| sex         | ENUM     |
| salary      | int      |
+-------------+----------+

Input:
+----+------+-----+--------+
| id | name | sex | salary |
+----+------+-----+--------+
| 1  | A    | m   | 2500   |
| 2  | B    | f   | 1500   |
| 3  | C    | m   | 5500   |
| 4  | D    | f   | 500    |
+----+------+-----+--------+

Output:
+----+------+-----+--------+
| id | name | sex | salary |
+----+------+-----+--------+
| 1  | A    | f   | 2500   |
| 2  | B    | m   | 1500   |
| 3  | C    | f   | 5500   |
| 4  | D    | m   | 500    |
+----+------+-----+--------+

👣 My Approaches
🔹 First Attempt (Basic CASE logic)

UPDATE Salary
SET sex = CASE
             WHEN sex = 'm' THEN 'f'
             WHEN sex = 'f' THEN 'm'
          END;

It worked fine, but I wondered if I could simplify it.

🔸 Second Attempt (Shorter CASE)

SET sex = CASE
             WHEN sex = 'm' THEN 'f'
             ELSE 'm'
          END;

This still gave the correct result — because sex only has 'm' and 'f', so ELSE 'm' is safe.

🟢 Final Attempt (IF-based)

UPDATE Salary
SET sex = IF(sex = 'm', 'f', 'm');

This version is short, clean, and very readable. I believe it's the most efficient and expressive for this case.

✅ I'm sticking with this as my final version (unless there's a hidden SQL performance nuance I missed — feel free to comment!).

💭 Reflection
Even a simple-looking problem made me think about different ways to write conditional updates. This helped me:

Practice CASE vs IF

Learn how to simplify logic without breaking correctness

Think about readability and maintainability in SQL

That’s it for this week!
Next time, I’ll share more problems, learnings, and maybe some frontend/devlog thoughts too. Thanks for reading! 💻✨