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https://www.hackerrank.com/domains/sql?filters%5Bskills%5D%5B%5D=SQL%20%28Intermediate%29 Solve SQL Code Challenges A special-purpose language designed for managing data held in a relational database. www.hackerrank.com intermediate ☆Binary Tree Nodes select N, case when P is null then "Root" when N not in (select distinct P from BST where P is not null) then "Leaf" else "Inner" end from BST ord..

HACKERRANK _ SQL https://www.hackerrank.com/domains/sql?filters%5Bskills%5D%5B%5D=SQL%20%28Basic%29 Solve SQL Code Challenges A special-purpose language designed for managing data held in a relational database. www.hackerrank.com SKILLS (BASIC / INTERMEDIATE / Advanced ) 中 BASIC ! Revising the Select Query I select * from CITY where POPULATION > 100000 and COUNTRYCODE = "USA" Revising the Select..

코드카데미(codecademy) SQL 연습해보기 https://www.codecademy.com/courses/learn-sql/lessons/manipulation/exercises/manipulation-review Cheating Sheet https://www.codecademy.com/learn/learn-sql/modules/learn-sql-manipulation/cheatsheet LESSON 1 Manipulation CREATE TABLE CREATE TABLE celebs ( id INTEGER, name TEXT, age INTEGER ); INSERT TABLE INSERT INTO celebs (id, name, age) VALUES (1, 'Justin Bieber', 22)..

■ 코드카데미(codecademy) SQL 연습해보기 https://www.codecademy.com/courses/learn-sql/lessons/multiple-tables/exercises/generalizations-multiple-tables ■ Cheating Sheets https://www.codecademy.com/learn/learn-sql/modules/learn-sql-multiple-tables/cheatsheet LESSON 4 : MULTIPLE TABLES JOIN (= Inner Join, 교집합) SELECT * FROM books JOIN authors ON books.author_id = authors.id; LEFT JOIN (= Outer Join) SELECT c..