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SQL Self Join
A SELF JOIN is a regular join, but the table is joined with itself.
Syntax
SELECT a.column_name, b.column_name
FROM table_name a, table_name b
WHERE condition;Example: SELF JOIN
SELECT a.name AS Employee, b.name AS Manager
FROM employees a, employees b
WHERE a.manager_id = b.id;This query selects employee names and their corresponding manager names from the same table.
Sample Table
Consider the following employees table:
| id | name | manager_id |
|----|-------------|------------|
| 1 | John Doe | 2 |
| 2 | Jane Smith | 4 |
| 3 | Mike Johnson| 2 |
| 4 | Emily Davis | NULL |Result of SELF JOIN
| Employee | Manager |
|-------------|-------------|
| John Doe | Jane Smith |
| Mike Johnson| Jane Smith |
| Jane Smith | Emily Davis |All employees and their corresponding managers are returned. If an employee does not have a manager, they are not included in the result.
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