Difference between INNER JOIN and OUTER JOIN in Postgresql

In Postgresql, the focus keyword 'INNER JOIN' and 'OUTER JOIN' are used in database queries to combine rows from two or more tables based on a related column between them.

INNER JOIN

INNER JOIN retrieves rows from both tables that have matching values in the specified column. It only includes the rows where the join condition is met.

OUTER JOIN

On the other hand, OUTER JOIN retrieves rows from both tables, even if there is no match found in the joined table. There are three types of OUTER JOINS in Postgresql: LEFT OUTER JOIN, RIGHT OUTER JOIN, and FULL OUTER JOIN.

LEFT OUTER JOIN includes all the rows from the left table, and the matched rows from the right table. RIGHT OUTER JOIN includes all the rows from the right table, and the matched rows from the left table. FULL OUTER JOIN includes all the rows when there is a match in either the left or right table.

Understanding the difference between INNER JOIN and OUTER JOIN is crucial in writing efficient and accurate SQL queries in Postgresql.