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[hackerrank] Prepare > SQL > Aggregation > Population Density Difference [문제] Query the difference between the maximum and minimum populations in CITY. Input Format The CITY table is described as follows: [MYSQL] [ORCALE] select max(population)-min(population) from city;

[hackerrank] Prepare > SQL > Aggregation > Japan Population [문제] Query the sum of the populations for all Japanese cities in CITY. The COUNTRYCODE for Japan is JPN. Input Format The CITY table is described as follows: [MYSQL] [ORCALE] select sum(population) from city where countrycode = 'JPN';

[hackerrank] Prepare > SQL > Aggregation > Average Population [문제] Query the average population for all cities in CITY, rounded down to the nearest integer. Input Format The CITY table is described as follows: [MYSQL] [ORCALE] select round(avg(population),0) from city;

[hackerrank] Prepare > SQL > Aggregation > Revising Aggregations - Averages [문제] Query the average population of all cities in CITY where District is California. Input Format The CITY table is described as follows: [MYSQL] [ORCALE] select avg(population) from city where district = 'California';

[hackerrank] Prepare > SQL > Aggregation > > Revising Aggregations - The Sum Function [문제] Query the total population of all cities in CITY where District is California. Input Format The CITY table is described as follows: [MYSQL] [ORCALE] select sum(population) from city where district = 'California';

[hackerrank] Prepare > SQL > Aggregation > Weather Observation Station 20 [문제] A median is defined as a number separating the higher half of a data set from the lower half. Query the median of the Northern Latitudes (LAT_N) from STATION and round your answer to decimal places. Input Format The STATION table is described as follows: where LAT_N is the northern latitude and LONG_W is the western l..

[hackerrank] Prepare > SQL > Aggregation > Revising Aggregations - The Count Function [문제] Query a count of the number of cities in CITY having a Population larger than . Input Format The CITY table is described as follows: [MYSQL] [ORCALE] select count(*) from city where population > 100000;

[hackerrank] Prepare > SQL > Advanced Select > New Companies [문제] Amber's conglomerate corporation just acquired some new companies. Each of the companies follows this hierarchy: Given the table schemas below, write a query to print the company_code, founder name, total number of lead managers, total number of senior managers, total number of managers, and total number of employees. Order your o..

[hackerrank] Prepare > SQL > Advanced Select > 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. In..

[hackerrank] Prepare > SQL > Advanced Select > Occupations [문제] Pivot the Occupation column in OCCUPATIONS so that each Name is sorted alphabetically and displayed underneath its corresponding Occupation. The output column headers should be Doctor, Professor, Singer, and Actor, respectively. Note: Print NULL when there are no more names corresponding to an occupation. Input Format The OCCUPATION..