Spatial Data Management with PostgreSQL and PostGIS https://gishub.org/sdm
ALTER TABLE cities
ALTER COLUMN population TYPE INT
USING population::integer
The examples below use the sample dataset - cities.csv
SELECT * FROM cities
SELECT * FROM cities LIMIT 10
SELECT name, country FROM cities
SELECT DISTINCT country FROM cities
SELECT COUNT(DISTINCT country) FROM cities
SELECT MAX(population) FROM cities
SELECT SUM(population) FROM cities
SELECT AVG(population) FROM cities
SELECT * FROM cities ORDER BY country
SELECT * FROM cities ORDER BY country ASC, population DESC
SELECT * FROM cities WHERE country='USA'
SELECT * FROM cities WHERE country='USA' OR country='CAN'
SELECT * FROM cities WHERE country='USA' AND population>1000000
SELECT * FROM cities WHERE country LIKE 'U%'
SELECT * FROM cities WHERE country LIKE '%A'
SELECT * FROM cities WHERE country LIKE '_S_'
SELECT * FROM cities WHERE country IN ('USA', 'CAN', 'CHN')
SELECT * FROM cities WHERE population BETWEEN 1000000 AND 10000000