MySQL 2外键到相同的主键

Question

So I have 2 tables; a task table and an employee table.

A task is created by an employee and maintains the id of the employee that creates it as creator_id.

A task is assigned to an employee and maintains the id of the employee it is assigned to as responsible_id.

The creator of the task and the employee it is assigned to can be different people.

How do I write a select statement that allows me to display the full names of both the employee that created the task and the employee that is assigned to it.

I think it might look something like this:

SELECT Task.Description, Employee1.name, Employee2.name
FROM Task, Employee Employee1, Employee Employee2
WHERE Task.creator_id = Employee1.id
AND Task.responsible_id = Employee2.id;

I have tried variations of this but it either returns errors or hits the memory limit.

Where am I going wrong?

Answer 1

From your description the query is correct but you should consider rewriting it to use explicit ANSI joins:

SELECT Task.Description, Employee1.name, Employee2.name
FROM Task
JOIN Employee Employee1 ON Task.creator_id = Employee1.id
JOIN Employee Employee2 ON Task.responsible_id = Employee2.id;

Sample SQL Fiddle