Joining Data in SQL
Maham Faisal Khan
Senior Content Developer, Data Science
INNER JOIN
ON
the id
fieldLEFT JOIN
will return all records in the left table, and those records in the right table that match on the joining field providedLEFT JOIN
ON
the id
fieldLEFT JOIN
ON
the id
fieldSELECT p1.country, prime_minister, president
FROM prime_ministers AS p1
LEFT JOIN presidents AS p2
USING(country);
Note. LEFT JOIN
can also be written as LEFT OUTER JOIN
.
| country | prime_minister | president |
|----------------|-------------------|-------------------------|
| Egypt | Mostafa Madbouly | Abdel Fattah el-Sisi |
| Portugal | Luís Montenegro | Marcelo Rebelo de Sousa |
| Pakistan | Shehbaz Sharif | Asif Ali Zardari |
| United Kingdom | Keir Starmer | null |
| India | Narendra Modi | Droupadi Murmu |
| Australia | Anthony Albanese | null |
...
RIGHT JOIN
ON
the id
fieldSELECT *
FROM left_table
RIGHT JOIN right_table
ON left_table.id = right_table.id;
Note. RIGHT JOIN
can also be written as RIGHT OUTER JOIN
.
SELECT p1.country, prime_minister, president
FROM prime_ministers AS p1
RIGHT JOIN presidents AS p2
USING(country);
| country | prime_minister | president |
|----------------|------------------|-------------------------|
| Egypt | Mostafa Madbouly | Abdel Fattah el-Sisi |
| Portugal | Luís Montenegro | Marcelo Rebelo de Sousa |
| USA | null | Joe Biden |
| Uruguay | null | Luis Lacalle Pou |
| Pakistan | Shehbaz Sharif | Asif Ali Zardari |
| Chile | null | Gabriel Boric |
| India | Narendra Modi | Droupadi Murmu |
RIGHT JOIN
is less commonly used than LEFT JOIN
RIGHT JOIN
can be re-written as a LEFT JOIN
LEFT JOIN
feels more intuitive to users when typing from left to rightJoining Data in SQL