How to use same field from a table twice in one query - mysql

Question

I have two tables: calls and employees. In the calls tables I have a field enter_emp_id and another follow_emp_id. They hold the values for which employee entered the call and which employee is assigned to the call. My second table employees has employee_id and employee fields. I am able to write a query to show results with an employee name for who entered the call, but not who it is assigned to. I do have other values in the query, but I need to get the 2nd employee name to show in the results. Here is what I am using so far:
SELECT
`calls`.`call_id`,
`calls`.`enter_date`,
`call_state`.`call_state`,
`customers`.`customer_name`,
`calls`.`comments`,
`employees`.`employee`,
`call_reasons`.`call_reason`
FROM
`customers`
INNER JOIN `calls` ON (`customers`.`customer_id` = `calls`.`customer_id`)
INNER JOIN `employees` ON (`employees`.`employee_id` = `calls`.`enter_emp_id`)
INNER JOIN `call_state` ON (`call_state`.`call_state_id` = `calls`.`call_state_id`)
INNER JOIN `call_reasons` ON (`call_reasons`.`call_reason_id` = `calls`.`call_reason_id`)
WHERE
`calls`.`call_id` = $call_id;

Answer 1

You need to join to the employee table TWICE... once for each employee id association, and use the ALIAS of the respective to get the values intended. And aliasing the tables and removal of unnecessary tick marks not required. Only needed for possible reserved word conflicts.
SELECT
c.call_id,
c.enter_date,
cs.call_state,
cust.customer_name,
c.comments,
entered.employee,
assigned.employee as AssignedEmployee,
cr.call_reason
FROM
calls c
INNER JOIN customers cust
ON c.customer_id = cust.customer_id
INNER JOIN employees entered
ON c.enter_emp_id = entered.employee_id
INNER JOIN employees assigned
ON c.enter_emp_id = assigned.employee_id
INNER JOIN call_state cs
ON c.call_state_id = cs.call_state_id
INNER JOIN call_reasons cr
ON c.call_reason_id = cr.call_reason_id
WHERE
c.call_id = $call_id;

Answer 2

I hope i understand you problem. You can use AS to change or shorten table name for sql usage
SELECT
`calls`.`call_id`,
`calls`.`enter_date`,
`call_state`.`call_state`,
`customers`.`customer_name`,
`calls`.`comments`,
`employees`.`employee`,
`assigned`.`employee` as assigned_employee,
`call_reasons`.`call_reason`
FROM
`customers`
INNER JOIN `calls` ON (`customers`.`customer_id` = `calls`.`customer_id`)
INNER JOIN `employees` ON (`employees`.`employee_id` = `calls`.`enter_emp_id`)
INNER JOIN `employees` AS `assigned` ON (`assigned`.`employee_id` = `calls`.`follow_emp_id`)
INNER JOIN `call_state` ON (`call_state`.`call_state_id` = `calls`.`call_state_id`)
INNER JOIN `call_reasons` ON (`call_reasons`.`call_reason_id` = `calls`.`call_reason_id`)
WHERE
`calls`.`call_id` = $call_id;

Answer 3

Thanks the following worked:
SELECT
c.call_id,
c.enter_date,
cs.call_state,
cust.customer_name,
c.comments,
entered.employee,
entered.employee,
cr.call_reason
FROM
calls c
INNER JOIN customers cust
ON c.customer_id = cust.customer_id
INNER JOIN employees entered
ON c.enter_emp_id = entered.employee_id
INNER JOIN employees assigned
ON c.enter_emp_id = assigned.employee_id
INNER JOIN call_state cs
ON c.call_state_id = cs.call_state_id
INNER JOIN call_reasons cr
ON c.call_reason_id = cr.call_reason_id
WHERE
c.call_id = $call_id;