HackerRank SQL Solutions

Disclaimer

This page contains solutions for all HackerRank SQL challenges which were passed successfully. There can be multiple ways of approaching solution to any problem. Please find the provided solutions for learning purposes only.

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Skills

	SQL (Basic)	SQL (Intermediate)	SQL (Advanced)
Number of Problems	40	14	4

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Domains

	Basic Select	Advanced Select	Aggregation	Basic Join	Advanced Join	Alternative Queries
Number of Problems	20	5	17	8	5	3

1. Basic Select

Sr No	Challenges	Language	Solution	Skills
1	Revising the Select Query I	MySQL	Revising-the-Select-Query-I	Basic
2	Revising the Select Query II	MySQL	Revising-the-Select-Query-II	Basic
3	Select All	MySQL	Select-All	Basic
4	Select By ID	MySQL	Select-By-ID	Basic
5	Japanese Cities' Attributes	MySQL	Japanese-Cities'-Attributes	Basic
6	Japanese Cities' Names	MySQL	Japanese-Cities'-Names	Basic
7	Weather Observation Station 1	MySQL	Weather-Observation-Station-1	Basic
8	Weather Observation Station 3	MySQL	Weather-Observation-Station-3	Basic
9	Weather Observation Station 4	MySQL	Weather-Observation-Station-4	Basic
10	Weather Observation Station 5	MySQL	Weather-Observation-Station-5	Intermediate
11	Weather Observation Station 6	MySQL	Weather-Observation-Station-6	Basic
12	Weather Observation Station 7	MySQL	Weather-Observation-Station-7	Basic
13	Weather Observation Station 8	MySQL	Weather-Observation-Station-8	Basic
14	Weather Observation Station 9	MySQL	Weather-Observation-Station-9	Basic
15	Weather Observation Station 10	MySQL	Weather-Observation-Station-10	Basic
16	Weather Observation Station 11	MySQL	Weather-Observation-Station-11	Basic
17	Weather Observation Station 12	MySQL	Weather-Observation-Station-12	Basic
18	Higher Than 75 Marks	MySQL	Higher-Than-75-Marks	Basic
19	Employee Names	MySQL	Employee-Names	Basic
20	Employee Salaries	MySQL	Employee-Salaries	Basic

2. Advanced Select

Sr No	Challenges	Language	Solution	Skills
1	Type of Triangle	MySQL	Type-of-Triangle	Basic
2	The PADS	MySQL	The-PADS	Basic
3	Occupations	MySQL	Occupations	Intermediate
4	Binary Tree Nodes	MySQL	Binary-Tree-Nodes	Intermediate
5	New Companies	MySQL	New-Companies	Intermediate

3. Aggregation

Sr No	Challenges	Language	Solution	Skills
1	Revising Aggregations - The Count Function	MySQL	Revising-Aggregations-The-Count-Function	Basic
2	Revising Aggregations - The Sum Function	MySQL	Revising-Aggregations-The-Sum-Function	Basic
3	Revising Aggregations - Averages	MySQL	Revising-Aggregations-Averages	Basic
4	Average Population	MySQL	Average-Population	Basic
5	Japan Population	MySQL	Japan-Population	Basic
6	Population Density Difference	MySQL	Population-Density-Difference	Basic
7	The Blunder	MySQL	The-Blunder	Basic
8	Top Earners	MySQL	Top-Earners	Basic
9	Weather Observation Station 2	MySQL	Weather-Observation-Station-2	Basic
10	Weather Observation Station 13	MySQL	Weather-Observation-Station-13	Basic
11	Weather Observation Station 14	MySQL	Weather-Observation-Station-14	Basic
12	Weather Observation Station 15	MySQL	Weather-Observation-Station-15	Basic
13	Weather Observation Station 16	MySQL	Weather-Observation-Station-16	Basic
14	Weather Observation Station 17	MySQL	Weather-Observation-Station-17	Basic
15	Weather Observation Station 18	MySQL	Weather-Observation-Station-18	Basic
16	Weather Observation Station 19	MySQL	Weather-Observation-Station-19	Basic
17	Weather Observation Station 20	MySQL	Weather-Observation-Station-20	Intermediate

4. Basic Join

Sr No	Challenges	Language	Solution	Skills
1	Population Census	MySQL	Population-Census	Basic
2	African Cities	MySQL	African-Cities	Basic
3	Average Population of Each Continent	MySQL	Average-Population-of-Each-Continent	Basic
4	The Report	MySQL	The-Report	Intermediate
5	Top Competitors	MySQL	Top-Competitors	Intermediate
6	Ollivander's Inventory	MySQL	Ollivander's-Inventory	Intermediate
7	Challenges	MySQL	Challenges	Intermediate
8	Contest Leaderboard	MySQL	Contest-Leaderboard	Intermediate

5. Advanced Join

Sr No	Challenges	Language	Solution	Skills
1	SQL Project Planning	MySQL	SQL-Project-Planning	Intermediate
2	Placements	MySQL	Placements	Intermediate
3	Symmetric Pairs	MySQL	Symmetric-Pairs	Intermediate
4	Interviews	MySQL	Interviews	Intermediate
5	15 Days of Learning SQL	MySQL	15-Days-of-Learning-SQL	Advanced

6. Alternative Queries

Sr No	Challenges	Language	Solution	Skills
1	Draw The Triangle 1	MySQL	Draw-The-Triangle-1	Advanced
2	Draw The Triangle 2	MySQL	Draw-The-Triangle-2	Advanced
3	Print Prime Numbers	MySQL	Print-Prime-Numbers	Advanced