Logo Studenta

Ayu_02-Pauta

Esta es una vista previa del archivo. Inicie sesión para ver el archivo original

USE world_x;
SELECT *
FROM city;
SELECT *
FROM country;
SELECT *
FROM countryinfo;
SELECT *
FROM countrylanguage;
-- Proyección 
SELECT id, name, countrycode, district, info
FROM city;
-- Proyección 
SELECT countrycode, language, percentage
FROM countrylanguage;
-- Seleccion
SELECT countrycode, language, percentage
FROM countrylanguage
WHERE percentage>10;
-- Union: 
SELECT language, percentage
FROM countrylanguage
UNION
SELECT countrycode, info
FROM city;
SELECT capital, code2
FROM country
UNION
SELECT district, name
FROM city;
-- join:
SELECT *
FROM country
JOIN city
ON country.code = city.countrycode;
SELECT *
FROM country
JOIN city
ON country.capital = city.id;
SELECT country.name, city.name
FROM country
JOIN city
ON country.capital = city.id;
SELECT country.name, countrylanguage.language, countrylanguage.percentage
FROM country
JOIN countrylanguage
ON country.code = countrylanguage.countrycode
WHERE percentage>20
ORDER BY percentage DESC;

Otros materiales