HAZEL

Weather Observation Station 7 >> 문제 Query the list of CITY names ending with vowels (a, e, i, o, u) from STATION. Your result cannot contain duplicates. Input Format The STATION table is described as follows: where LAT_N is the northern latitude and LONG_W is the western longitude. >> 기본적으로 푸는 방법 SELECT DISTINCT city FROM station WHERE city LIKE '%a' OR city LIKE '%e' OR city LIKE '%i' OR city L..

Weather Observation Station 6 >> 문제 Query the list of CITY names starting with vowels (i.e., a, e, i, o, or u) from STATION. Your result cannot contain duplicates. Input Format The STATION table is described as follows: where LAT_N is the northern latitude and LONG_W is the western longitude. >> 기본적으로 푸는 방법 select DISTINCT city FROM station WHERE city LIKE 'a%' OR city LIKE 'e%' OR city LIKE 'i%..

185. Department Top Three Salaries >> 문제 The Employee table holds all employees. Every employee has an Id, and there is also a column for the department Id. +----+-------+--------+--------------+ | Id | Name | Salary | DepartmentId | +----+-------+--------+--------------+ | 1 | Joe | 85000 | 1 | | 2 | Henry | 80000 | 2 | | 3 | Sam | 60000 | 2 | | 4 | Max | 90000 | 1 | | 5 | Janet | 69000 | 1 | |..

180. Consecutive Numbers >> 문제 +-------------+---------+ | Column Name | Type | +-------------+---------+ | id | int | | num | varchar | +-------------+---------+ id is the primary key for this table. Write an SQL query to find all numbers that appear at least three times consecutively. Return the result table in any order. The query result format is in the following example: Logs table: +----+-..

The Report >> 문제 You are given two tables: Students and Grades. Students contains three columns ID, Name and Marks. Grades contains the following data: Ketty gives Eve a task to generate a report containing three columns: Name, Grade and Mark. Ketty doesn't want the NAMES of those students who received a grade lower than 8. The report must be in descending order by grade -- i.e. higher grades ar..

Challenges >> 문제 Julia asked her students to create some coding challenges. Write a query to print the hacker_id, name, and the total number of challenges created by each student. Sort your results by the total number of challenges in descending order. If more than one student created the same number of challenges, then sort the result by hacker_id. If more than one student created the same numb..

184. Department Highest Salary >> 문제 The Employee table holds all employees. Every employee has an Id, a salary, and there is also a column for the department Id. +----+-------+--------+--------------+ | Id | Name | Salary | DepartmentId | +----+-------+--------+--------------+ | 1 | Joe | 70000 | 1 | | 2 | Jim | 90000 | 1 | | 3 | Henry | 80000 | 2 | | 4 | Sam | 60000 | 2 | | 5 | Max | 90000 | 1..

196. Delete Duplicate Emails >> 문제 Write a SQL query to delete all duplicate email entries in a table named Person, keeping only unique emails based on its smallest Id. +----+------------------+ | Id | Email | +----+------------------+ | 1 | john@example.com | | 2 | bob@example.com | | 3 | john@example.com | +----+------------------+ Id is the primary key column for this table. For example, afte..

627. Swap Salary >> 문제 +-------------+----------+ | Column Name | Type | +-------------+----------+ | id | int | | name | varchar | | sex | ENUM | | salary | int | +-------------+----------+ id is the primary key for this table. The sex column is ENUM value of type ('m', 'f'). The table contains information about an employee. Write an SQL query to swap all 'f' and 'm' values (i.e., change all 'f..

Binary Tree Nodes >> 문제 You are given a table, BST, containing two columns: N and P, where N represents the value of a node in Binary Tree, and P is the parent of N. Write a query to find the node type of Binary Tree ordered by the value of the node. Output one of the following for each node: Root: If node is root node. Leaf: If node is leaf node. Inner: If node is neither root nor leaf node. Sa..