SQL

Revising the Select Query I/II / Select All / Select By ID / Japanese Cities' Attributes / Japanese Cities' Names

basic 3문제

Intermediate 1문제

Basic 4문제 - LIKE 연산 / 정규표현식

Basic 3문제

Higher Than 75 Marks / Employee Names / Employee Salaries

⭐ Type of Triangle

Revising Aggregations - The Count Function, The Sum Function, Averages / Average Population / Japan Population / Population Density Difference

The Blunder

⭐ Top Earners

해커랭크에서는 CASE ... END AS col_name 같이 컬럼명이 필요하다

Intermediate

Intermediate

The Report https://www.hackerrank.com/challenges/the-report Lesson & Learned 잘못 작성한 쿼리 SELECT CASE WHEN grade < 8 THEN ELSE name END , grade , marks FROM Students s INNER JOIN Grades ...

GROUP BY절 에러

Ollivander's Inventory https://www.hackerrank.com/challenges/harry-potter-and-wands Harry Potter and his friends are at Ollivander's with Ron, finally replacing Charlie's old broken wand. Hermione de...

Challenges https://www.hackerrank.com/challenges/challenges Julia asked her students to create some coding challenges. Write a query to print the hackerid, name, and the total number of challenges cre...

Symmetric Pairs https://www.hackerrank.com/challenges/symmetric-pairs You are given a table, Functions, containing two columns: X and Y. Two pairs (X1, Y1) and (X2, Y2) are said to be symmetric pairs ...

Alternative Queries 문제 RECURSIVE(CTE: Common Table Expressions) 와 REPEAT( )

⭐ Hard

postgreSQL

postgreSQL

postgreSQL

postgreSQL

postgreSQL

postgreSQL

RFM 분석

lv1

lv1

MySQL

MySQL