SQL

Wed, 01 Oct 2025 21:29:01 +0800

Joining Data in SQL

Inner JOINs

SELECT *
FROM cities
-- Inner join to countries
INNER JOIN countries
-- Match on country codes
ON cities.country_code = countries.code;

-- Select name fields (with alias) and region 
SELECT city.name, country.name, region
FROM cities AS city
INNER JOIN countries AS country
ON city.country_code = country.code;

-- Select fields with aliases
SELECT c.code AS country_code, c.name, e.year, e.inflation_rate 
FROM countries AS c
-- Join to economies (alias e)
INNER JOIN economies AS e 
-- Match on code field using table aliases
ON c.code = e.code;

SELECT c.name AS country, l.name AS language, official
FROM countries AS c
INNER JOIN languages AS l
-- Match using the code column
USING (code);

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SQL

Joining Data in SQL

Inner JOINs