How do SQL JOINs work?

February 19, 2026Computer Science

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February 19, 2026

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$orders.user_id — returns only users who have orders.$

SQL JOINs combine rows from multiple tables based on related columns. Types: INNER JOIN: only matching rows from both tables. LEFT JOIN: all rows from left table + matching from right (NULL if no match). RIGHT JOIN: opposite of LEFT. FULL OUTER JOIN: all rows from both, NULLs where no match. CROSS JOIN: every combination (cartesian product). Example: SELECT users.name, orders.total FROM users INNER JOIN orders ON users.id = orders.user_id — returns only users who have orders.

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SQL JOINs combine rows from multiple tables based on related columns. Types: INNER JOIN: only matching rows from both tables.

Asked on February 19, 2026Computer Science

This computer science problem involves algorithmic thinking and programming concepts. The solution below explains the approach, logic, and implementation step by step.

ScanSolve AI AnswerAnswered on February 19, 2026

SQL JOINs combine rows from multiple tables based on related columns. Types: INNER JOIN: only matching rows from both tables. LEFT JOIN: all rows from left table + matching from right (NULL if no match). RIGHT JOIN: opposite of LEFT. FULL OUTER JOIN: all rows from both, NULLs where no match. CROSS JOIN: every combination (cartesian product). Example: SELECT users.name, orders.total FROM users INNER JOIN orders ON users.id = orders.user_id — returns only users who have orders.