In SQL, a join is a way to combine data from two or more tables based on a common field. There are several different types of joins that you can use in SQL, each with its own specific behavior and use cases.
Here are the most common types of joins in SQL:
- INNER JOIN: An inner join returns only the rows that match the join condition in both tables. It is the most commonly used type of join, and is used to combine data from two tables where there is a one-to-one or many-to-one relationship.
- LEFT JOIN: A left join returns all the rows from the left table, and any matching rows from the right table. If there is no match, NULL values are returned for the right table. A left join is used to combine data from two tables where there is a one-to-many relationship.
- RIGHT JOIN: A right join is similar to a left join, but returns all the rows from the right table and any matching rows from the left table. If there is no match, NULL values are returned for the left table.
- FULL OUTER JOIN: A full outer join returns all the rows from both tables, regardless of whether there is a match. If there is no match, NULL values are returned for the non-matching columns. A full outer join is used to combine data from two tables where there is a one-to-one, one-to-many, or many-to-many relationship.
- CROSS JOIN: A cross join returns the Cartesian product of the two tables, which is the set of all possible combinations of rows from the two tables. A cross join does not use a join condition, and is used to generate a large number of rows for testing or other purposes.
You can use these different types of joins to combine data from multiple tables in a variety of ways, depending on the needs of your query. I hope this helps!