Can you explain the differences between table join types in SQL?

In SQL, there are different types of joins that allow combining data from two or more tables:

• INNER JOIN — returns only the rows where there are matches in both tables.
• LEFT JOIN (or LEFT OUTER JOIN) — returns all rows from the left table and matching rows from the right; if there are no matches, NULLs will appear in the right table's columns.
• RIGHT JOIN (or RIGHT OUTER JOIN) — the opposite, returns all rows from the right table and matching rows from the left.
• FULL JOIN (or FULL OUTER JOIN) — returns all rows from both tables, matching where possible, filling NULLs where there is no match.
• CROSS JOIN — Cartesian product of two tables, each row of the first table is combined with each row of the second.

Example:

SELECT * FROM A
INNER JOIN B ON A.id = B.a_id;

Returns only the rows where A.id matches B.a_id.

Understanding the differences is important for constructing correct queries and obtaining the desired data.