📒 SQL HackerRank Practice Questions

This repository includes my answers for the SQL practice questions provided by HackerRank.

The questions can be answered in 4 different types of SQL flavours and I decided to answer them using MySQL.

The questions are divided into 6 types:

• Basic Select
• Aggregation
• Basic Joins
• Advanced Select
• Advanced Joins
• Alternative Queries

So far I have answered 45 out of 58 questions. The repository will get updated from time to time when I answer more of the questions.

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Basic Select 🔎

Number	Question	Solution
1	Revising the Select Query I	Click Here
2	Revising the Select Query II	Click Here
3	Select All	Click Here
4	Select By ID	Click Here
5	Japanese Cities' Attributes	Click Here
6	Japanese Cities' Names	Click Here
7	Weather Observation Station 1	Click Here
8	Weather Observation Station 3	Click Here
9	Weather Observation Station 4	Click Here
10	Weather Observation Station 5	Click Here
11	Weather Observation Station 6	Click Here
12	Weather Observation Station 7	Click Here
13	Weather Observation Station 8	Click Here
14	Weather Observation Station 9	Click Here
15	Weather Observation Station 10	Click Here
16	Weather Observation Station 11	Click Here
17	Weather Observation Station 12	Click Here
18	Higher Than 75 Marks	Click Here
19	Employee Names	Click Here
20	Employee Salaries	Click Here

Aggregation 🧱

Number	Question	Solution
1	Revising Aggregations - The Count Function	Click Here
2	Revising Aggregations - The Sum Function	Click Here
3	Revising Aggregations - Averages	Click Here
4	Average Population	Click Here
5	Japan Population	Click Here
6	Population Density Difference	Click Here
7	The Blunder	Click Here
8	Top Earners	Click Here
9	Weather Observation Station 13	Click Here
10	Weather Observation Station 14	Click Here
11	Weather Observation Station 15	Click Here
12	Weather Observation Station 16	Click Here
13	Weather Observation Station 17	Click Here
14	Weather Observation Station 18	Click Here
15	Weather Observation Station 19	Click Here
16	Weather Observation Station 20	Click Here

Basic Joins 🧲

Number	Question	Solution
1	Population Census	Click Here
2	African Cities	Click Here
3	Average Population of Each Continent	Click Here
4	The Report	Click Here
5	Top Competitors	Click Here
6	Ollivander's Inventory	Click Here
7	Contest Leaderboard	Click Here
8	Challenges	Coming Soon

Advanced Select 🔬

Number	Question	Solution
1	Type of Triangle	Click Here
2	Occupations	Coming Soon
3	Binary Tree Nodes	Coming Soon
4	New Companies	Coming Soon
5	The PADS	Coming Soon

Advanced Join 🗃

Number	Question	Solution
1	SQL Project Planning	Coming Soon
2	Placements	Coming Soon
3	Symmetric Pairs	Coming Soon
4	Interviews	Coming Soon
5	15 Days of Learning SQL	Coming Soon

Alternative Queries 📝

Number	Question	Solution
1	Draw The Triangle 1	Coming Soon
2	Draw The Triangle 2	Coming Soon
3	Print Prime Numbers	Coming Soon