Hacker Rank SQL

Weather Observation Station 4 Solution

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Also visit:ย  Weather Observation Station 3 Solution


 

Problem

Find the difference between the total number ofย CITYย entries in the table and the number of distinctย CITYย entries in the table.

The STATION table is described as follows:

STATION

Field Type
ID NUMBER
CITY VARCHAR2(21)
STATE VARCHAR2(2)
LAT_N NUMBER
LONG_W NUMBER

whereย LAT_Nย is the northern latitude andย LONG_Wย is the western longitude.

For example, if there are three records in the table withย CITYย values โ€˜New Yorkโ€™, โ€˜New Yorkโ€™, โ€˜Bengalaruโ€™, there are 2 different city names: โ€˜New Yorkโ€™ and โ€˜Bengalaruโ€™. The query returnsย 1, becauseย 
total number of records โ€“ number of unique city names = 3 โ€“ 2 = 1.

 

Solution โ€“ Weather Observation Station 4

MySQL Code
SELECT COUNT(CITY) - COUNT(DISTINCT CITY) FROM STATION;

 


Weather observations

Basic weather observation instruments include thermometers, rain gauges, barometers, and anemometers (wind speed meters).

What are the four types of weather observations?

There are four types of weather observations: surface, upper air, radar, and satellite.

What is weather observation stations?

A weather station is a facility, either on land or sea, with instruments and equipment for measuring atmospheric conditions to provide information for weather forecasts and to study the weather and climate.

Who observes weather?

A meteorologist is a physical scientist who observes, studies, or forecasts the weather.

How do you observe weather?

This is done by examining a large quantity of observation data including surface observations, satellite imagery, radar data, radiosonde data, upper-air data, wind profilers, aircraft observations, river gauges, and simply looking outside.

 

 

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