SQL · Joins and set operations

left join

Keeps every left row and fills missing right columns with NULL.

sqlRunnable example sql course

Syntax

from a left join b on …

Example

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WITH courses(id, title) AS (VALUES (1, 'HTML'), (2, 'CSS')),
     lessons(course_id, title) AS (VALUES (1, 'Intro'))
SELECT c.title, l.title AS lesson
FROM courses c LEFT JOIN lessons l ON l.course_id = c.id;

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left join

Example

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