# Weather Observation Station 4 Solution

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Also visit:  Weather Observation Station 3 Solution

#### Problem

Find the difference between the total number of CITY entries in the table and the number of distinct CITY entries in the table.

The STATION table is described as follows:

STATION

where LAT_N is the northern latitude and LONG_W is the western longitude.

For example, if there are three records in the table with CITY values ‘New York’, ‘New York’, ‘Bengalaru’, there are 2 different city names: ‘New York’ and ‘Bengalaru’. The query returns 1, because
total number of records – number of unique city names = 3 – 2 = 1.

## Solution – 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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