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PostgreSQL Table Relations

PostgreSQL supports standard SQL joins and set operations.

1. Joins​

INNER JOIN​

Returns rows when there is a match in both tables.

LEFT [OUTER] JOIN​

Returns all rows from the left table, and the matched rows from the right table.

RIGHT [OUTER] JOIN​

Returns all rows from the right table, and the matched rows from the left table.

FULL [OUTER] JOIN​

Returns all rows when there is a match in either left or right table.

CROSS JOIN​

Returns the Cartesian product of the two tables.

2. Set Operations​

UNION​

Combines the result of two or more SELECT statements (removes duplicates). Use UNION ALL to keep duplicates.

INTERSECT​

Returns only the rows that are present in both result sets.

EXCEPT​

Returns rows from the first result set that are not present in the second.

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