DATABASE SYSTEM DESIGN AND MANAGEMENT

Full Answer Section

This query will return all possible combinations of rows from the table1 and table2 tables.

Recursive join:

A recursive join is a type of join that is used to traverse a tree-like structure. It works by joining a table to itself, with a recursive WHERE clause that specifies the parent-child relationship between the rows.

For example, the following query will return all employees and their managers, recursively:

WITH RECURSIVE employees (
  id,
  name,
  manager_id
) AS (
  SELECT
    id,
    name,
    NULL AS manager_id
  FROM employees
  WHERE manager_id IS NULL
  UNION ALL
  SELECT
    e.id,
    e.name,
    e.manager_id
  FROM employees e
  INNER JOIN employees m
    ON e.manager_id = m.id
)
SELECT *
FROM employees;

Sample Solution

• LEFT JOIN: Returns all rows from the left table, even if there are no matching rows in the right table. The rows in the right table that do not have a match in the left table will have NULL values in the columns from the left table.
• RIGHT JOIN: Returns all rows from the right table, even if there are no matching rows in the left table. The rows in the left table that do not have a match in the right table will have NULL values in the columns from the right table.
• FULL OUTER JOIN: Returns all rows from both tables, even if there are no matching rows in the other table. The rows in each table that do not have a match in the other table will have NULL values in the columns from the other table.