Question

I have a table called employee with a Primary Key column of ID and a column called supervisorID, which is a reference back to the same table referencing a person. I want to show the supervisorID as the persons name that its referencing instead of the ID.

I want to select * from the table employee but reference the SupervisorID as a persons name from the same table.

Answer 1

SELECT e.ID, e.name AS Employee, s.name AS Supervisor 
FROM employee e 
  INNER JOIN employee s 
  ON s.ID = e.supervisorID 
ORDER BY e.ID;

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Here is more color on how to test this:

mysql> CREATE TABLE employee (ID INT NOT NULL AUTO_INCREMENT, supervisorID INT NOT NULL DEFAULT '1', name VARCHAR(48) NOT NULL, PRIMARY KEY (ID));
Query OK, 0 rows affected (0.01 sec)


mysql> INSERT INTO employee VALUES (1, 1, "The Boss"), (2,1, "Some Manager"), (3,2, "Some Worker"), (4,2, "Another Worker");
Query OK, 4 rows affected (0.00 sec)
Records: 4  Duplicates: 0  Warnings: 0


mysql> SELECT e.ID, e.name AS Employee, s.name AS Supervisor
FROM employee e INNER JOIN employee s
ON s.ID = e.supervisorID ORDER BY e.ID;
+----+----------------+--------------+
| ID | Employee       | Supervisor   |
+----+----------------+--------------+
|  1 | The Boss       | The Boss     |
|  2 | Some Manager   | The Boss     |
|  3 | Some Worker    | Some Manager |
|  4 | Another Worker | Some Manager |
+----+----------------+--------------+
4 rows in set (0.01 sec)

mysql>