The difference between inner joins and outer joins in SQL

In this article, we will understand the difference between inner join and outer join in SQL.

Inner join

• clause uses "INNER JOIN" and "JOIN".

• It returns a combined tuple of two or more tables.

• When there are no common attributes, the result is empty.

• "INNER JOIN" works faster than "OUTER" if the number of tuples is larger JOIN'.

• Used when detailed information about a specific property is required.

• 'JOIN' and 'INNER JOIN' work the same way.

Syntax

SELECT *
FROM table_1 INNER JOIN / JOIN table_2
ON table_1.column_name = table_2.column_name;

Outer Join

• Returns the combined tuple of the specified table.

• Returns even if the "JOIN" condition fails.

• You can use the clauses LEFT OUTER JOIN, RIGHT OUTER JOIN, FULL OUTER JOIN.

• Does not depend on public properties.

• If the property is empty , then NULL is placed instead of blank.

• Compared with "INNER JOIN", "OUTER JOIN" is slower.

• It is Use when complete information is required.

  li>

• FULL OUTER JOIN and FULL JOIN clauses work the same way.

Syntax

SELECT *
FROM table_1 LEFT OUTER JOIN / RIGHT OUTER JOIN /
FULL OUTER JOIN / FULL JOIN table_2 ON
Table_1.column_name = table_2.column_name;

The above is the detailed content of The difference between inner joins and outer joins in SQL. For more information, please follow other related articles on the PHP Chinese website!