Which joins have you used?

In SQL, the most common join types are INNER JOIN, LEFT OUTER JOIN, RIGHT OUTER JOIN, FULL OUTER JOIN, CROSS JOIN, SELF JOIN, and NATURAL JOIN. An INNER JOIN returns rows that have matching values in both tables. LEFT OUTER JOIN returns all rows from the left table and matched rows from the right table, filling with NULLs where no match exists. RIGHT OUTER JOIN is the opposite of LEFT. FULL OUTER JOIN returns all rows when there is a match in either table. CROSS JOIN produces the Cartesian product of two tables. SELF JOIN is a join of a table with itself, useful for hierarchical data. NATURAL JOIN automatically joins on columns with the same name. Each type is chosen based on the relationship between the tables and the desired result set.