HackerRank-SQL-Solutions

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HackerRank-SQL-Solutions

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This repository contains my solutions to HackerRank SQL challenges solved using MySQL, covering basic to advanced SQL concepts including joins, aggregations, subqueries, and window functions.

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# [HackerRank](https://www.hackerrank.com/profile/laxmimewada47)

## Description

This repository contains my solutions to SQL challenges from HackerRank executed in the MySQL environment.

The repository covers:
- Easy SQL Problems
- Medium SQL Problems
- Hard SQL Problems
- Query Optimization
- Joins & Aggregations
- Window Functions
- Subqueries
- CTEs

## Domains

### Basic Select Challenges

| No. | Challenge | Solution |
|-----|------------|----------|
| 1 | [Revising the Select Query I](https://www.hackerrank.com/challenges/revising-the-select-query/problem) | [SQL](./Basic%20Select/Revising_the_Select_Query_I.sql) |
| 2 | [Revising the Select Query II](https://www.hackerrank.com/challenges/revising-the-select-query-2/problem) | [SQL](./Basic%20Select/Revising_the_Select_Query_II.sql) |
| 3 | [Select All](https://www.hackerrank.com/challenges/select-all-sql/problem) | [SQL](./Basic%20Select/Select_All.sql) |
| 4 | [Select By ID](https://www.hackerrank.com/challenges/select-by-id/problem) | [SQL](./Basic%20Select/Select_By_ID.sql) |
| 5 | [Japanese Cities' Attributes](https://www.hackerrank.com/challenges/japanese-cities-attributes/problem) | [SQL](./Basic%20Select/Japanese_Cities_Attributes.sql) |
| 6 | [Japanese Cities' Names](https://www.hackerrank.com/challenges/japanese-cities-name/problem) | [SQL](./Basic%20Select/Japanese_Cities_Names.sql) |
| 7 | [Weather Observation Station 1](https://www.hackerrank.com/challenges/weather-observation-station-1/problem) | [SQL](./Basic%20Select/Weather_Observation_Station_1.sql) |
| 8 | [Weather Observation Station 3](https://www.hackerrank.com/challenges/weather-observation-station-3/problem) | [SQL](./Basic%20Select/Weather_Observation_Station_3.sql) |
| 9 | [Weather Observation Station 4](https://www.hackerrank.com/challenges/weather-observation-station-4/problem) | [SQL](./Basic%20Select/Weather_Observation_Station_4.sql) |
| 10 | [Weather Observation Station 5](https://www.hackerrank.com/challenges/weather-observation-station-5/problem) | [SQL](./Basic%20Select/Weather_Observation_Station_5.sql) |
| 11 | [Weather Observation Station 6](https://www.hackerrank.com/challenges/weather-observation-station-6/problem) | [SQL](./Basic%20Select/Weather_Observation_Station_6.sql) |
| 12 | [Weather Observation Station 7](https://www.hackerrank.com/challenges/weather-observation-station-7/problem) | [SQL](./Basic%20Select/Weather_Observation_Station_7.sql) |
| 13 | [Weather Observation Station 8](https://www.hackerrank.com/challenges/weather-observation-station-8/problem) | [SQL](./Basic%20Select/Weather_Observation_Station_8.sql) |
| 14 | [Weather Observation Station 9](https://www.hackerrank.com/challenges/weather-observation-station-9/problem) | [SQL](./Basic%20Select/Weather_Observation_Station_9.sql) |
| 15 | [Weather Observation Station 10](https://www.hackerrank.com/challenges/weather-observation-station-10/problem) | [SQL](./Basic%20Select/Weather_Observation_Station_10.sql) |
| 16 | [Weather Observation Station 11](https://www.hackerrank.com/challenges/weather-observation-station-11/problem) | [SQL](./Basic%20Select/Weather_Observation_Station_11.sql) |
| 17 | [Weather Observation Station 12](https://www.hackerrank.com/challenges/weather-observation-station-12/problem) | [SQL](./Basic%20Select/Weather_Observation_Station_12.sql) |
| 18 | [Higher Than 75 Marks](https://www.hackerrank.com/challenges/more-than-75-marks/problem) | [SQL](./Basic%20Select/Higher_Than_75_Marks.sql) |
| 19 | [Employee Names](https://www.hackerrank.com/challenges/name-of-employees/problem) | [SQL](./Basic%20Select/Employee_Names.sql) |
| 20 | [Employee Salaries](https://www.hackerrank.com/challenges/salary-of-employees/problem) | [SQL](./Basic%20Select/Employee_Salaries.sql) |

### Advanced Select Challenges

| No. | Challenge | Solution |
|-----|------------|----------|
| 1 | [Type of Triangle](https://www.hackerrank.com/challenges/what-type-of-triangle/problem) | [SQL](./Advanced%20Select/Type_of_Triangle.sql) |
| 2 | [The PADS](https://www.hackerrank.com/challenges/the-pads/problem) | [SQL](./Advanced%20Select/The_PADS.sql) |
| 3 | [Occupations](https://www.hackerrank.com/challenges/occupations/problem) | [SQL](./Advanced%20Select/Occupations.sql) |
| 4 | [Binary Tree Nodes](https://www.hackerrank.com/challenges/binary-search-tree-1/problem) | [SQL](./Advanced%20Select/Binary_Tree_Nodes.sql) |
| 5 | [New Companies](https://www.hackerrank.com/challenges/the-company/problem) | [SQL](./Advanced%20Select/New_Companies.sql) |

### Aggregation Challenges

| No. | Challenge | Solution |
|-----|------------|----------|
| 1 | [Revising Aggregations - The Count Function](https://www.hackerrank.com/challenges/revising-aggregations-the-count-function/problem) | [SQL](./Aggregation/Revising_Aggregations_The_Count_Function.sql) |
| 2 | [Revising Aggregations - The Sum Function](https://www.hackerrank.com/challenges/revising-aggregations-sum/problem) | [SQL](./Aggregation/Revising_Aggregations_The_Sum_Function.sql) |
| 3 | [Revising Aggregations - Averages](https://www.hackerrank.com/challenges/revising-aggregations-the-average-function/problem) | [SQL](./Aggregation/Revising_Aggregations_Averages.sql) |
| 4 | [Average Population](https://www.hackerrank.com/challenges/average-population/problem) | [SQL](./Aggregation/Average_Population.sql) |
| 5 | [Japan Population](https://www.hackerrank.com/challenges/japan-population/problem) | [SQL](./Aggregation/Japan_Population.sql) |
| 6 | [Population Density Difference](https://www.hackerrank.com/challenges/population-density-difference/problem) | [SQL](./Aggregation/Population_Density_Difference.sql) |
| 7 | [The Blunder](https://www.hackerrank.com/challenges/the-blunder/problem) | [SQL](./Aggregation/The_Blunder.sql) |
| 8 | [Top Earners](https://www.hackerrank.com/challenges/earnings-of-employees/problem) | [SQL](./Aggregation/Top_Earners.sql) |
| 9 | [Weather Observation Station 2](https://www.hackerrank.com/challenges/weather-observation-station-2/problem) | [SQL](./Aggregation/Weather_Observation_Station_2.sql) |
| 10 | [Weather Observation Station 13](https://www.hackerrank.com/challenges/weather-observation-station-13/problem) | [SQL](./Aggregation/Weather_Observation_Station_13.sql) |
| 11 | [Weather Observation Station 14](https://www.hackerrank.com/challenges/weather-observation-station-14/problem) | [SQL](./Aggregation/Weather_Observation_Station_14.sql) |
| 12 | [Weather Observation Station 15](https://www.hackerrank.com/challenges/weather-observation-station-15/problem) | [SQL](./Aggregation/Weather_Observation_Station_15.sql) |
| 13 | [Weather Observation Station 16](https://www.hackerrank.com/challenges/weather-observation-station-16/problem) | [SQL](./Aggregation/Weather_Observation_Station_16.sql) |
| 14 | [Weather Observation Station 17](https://www.hackerrank.com/challenges/weather-observation-station-17/problem) | [SQL](./Aggregation/Weather_Observation_Station_17.sql) |
| 15 | [Weather Observation Station 18](https://www.hackerrank.com/challenges/weather-observation-station-18/problem) | [SQL](./Aggregation/Weather_Observation_Station_18.sql) |
| 16 | [Weather Observation Station 19](https://www.hackerrank.com/challenges/weather-observation-station-19/problem) | [SQL](./Aggregation/Weather_Observation_Station_19.sql) |
| 17 | [Weather Observation Station 20](https://www.hackerrank.com/challenges/weather-observation-station-20/problem) | [SQL](./Aggregation/Weather_Observation_Station_20.sql) |

## Basic Join Challenges

| No. | Challenge | Solution |
|-----|------------|----------|
| 1 | [Asian Population](https://www.hackerrank.com/challenges/asian-population/problem) | [SQL](./Basic%20Join/Asian_Population.sql) |
| 2 | [African Cities](https://www.hackerrank.com/challenges/african-cities/problem) | [SQL](./Basic%20Join/African_Cities.sql) |
| 3 | [Average Population of Each Continent](https://www.hackerrank.com/challenges/average-population-of-each-continent/problem) | [SQL](./Basic%20Join/Average_Population_of_Each_Continent.sql) |
| 4 | [The Report](https://www.hackerrank.com/challenges/the-report/problem) | [SQL](./Basic%20Join/The_Report.sql) |
| 5 | [Top Competitors](https://www.hackerrank.com/challenges/full-score/problem) | [SQL](./Basic%20Join/Top_Competitors.sql) |
| 6 | [Ollivander's Inventory](https://www.hackerrank.com/challenges/harry-potter-and-wands/problem) | [SQL](./Basic%20Join/Ollivanders_Inventory.sql) |
| 7 | [Challenges](https://www.hackerrank.com/challenges/challenges/problem) | [SQL](./Basic%20Join/Challenges.sql) |
| 8 | [Contest Leaderboard](https://www.hackerrank.com/challenges/contest-leaderboard/problem) | [SQL](./Basic%20Join/Contest_Leaderboard.sql) |

### Advanced Join Challenges

| No. | Challenge | Solution |
|-----|------------|----------|
| 1 | [SQL Project Planning](https://www.hackerrank.com/challenges/sql-projects/problem) | [SQL](./Advanced%20Join/SQL_Project_Planning.sql) |
| 2 | [Placements](https://www.hackerrank.com/challenges/placements/problem) | [SQL](./Advanced%20Join/Placements.sql) |
## References

- [HackerRank SQL Practice](https://www.hackerrank.com/domains/sql)  
- [MySQL Documentation](https://dev.mysql.com/doc/)  
- [W3Schools SQL Tutorial](https://www.w3schools.com/sql/)  
- [GeeksforGeeks SQL Articles](https://www.geeksforgeeks.org/sql-tutorial/)

## Features & Mentions

- Structured solutions categorized by SQL topics  
- Covers basic, intermediate, and advanced SQL challenges  
- MySQL-compatible queries with clean formatting  
- Includes direct links to HackerRank problems  
- Built as part of my SQL and data analytics learning journey

## License

This repository is licensed under the [MIT License](https://opensource.org/licenses/MIT) - see the [LICENSE](./LICENSE) file for more details.

## Connect With Me
### LinkedIn
[LinkedIn](https://www.linkedin.com/in/laxmi-mewada29/)

### HackerRank
[HackerRank](https://www.hackerrank.com/profile/laxmimewada47)

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