How do connection types differ in SQL and what are their features?

In SQL, there are different types of joins that allow you to combine data from multiple 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 the matching rows from the right table; if there is no match, the result is NULL on the right side.
• RIGHT JOIN — similar to LEFT JOIN, but returns all rows from the right table.
• FULL JOIN (FULL OUTER JOIN) — returns all rows from both tables, filling in NULLs where there are no matches.

Example of INNER JOIN:

SELECT employees.name, departments.name
FROM employees
INNER JOIN departments ON employees.department_id = departments.id;

This query will return the names of employees and their departments only for those employees who have an assigned department.