Need to find the employees who have switched jobs atleast twice

Question

I am trying the following query on the tables which are described below:

SELECT * FROM job_history INNER JOIN employees
ON job_history.employee_id = employees.employee_id
WHERE employee_ID IN
    (SELECT employee_id FROM

        (SELECT employee_id, COUNT(employee_id) AS cnt
         FROM job_history
         GROUP BY employee_id
         HAVING cnt >= 2) INNER
    )    
    OUTER;

But I get an error in MySQL, that every derived table must have its own alias

We have a table job_history(employee_id, start_date, end_date, job_id, department_id) containing the following data:

'102', '1993-01-13', '1998-06-24', 'IT_PROG', '60'
'101', '1989-09-21', '1993-10-27', 'AC_ACCOUNT', '110'
'101', '1993-10-28', '1997-03-15', 'AC_MGR', '110'
'201', '1996-02-17', '1999-12-19', 'MK_REP', '20'
'114', '1998-03-24', '1999-12-31', 'ST_CLERK', '50'
'122', '1999-01-01', '1999-12-31', 'ST_CLERK', '50'
'200', '1987-09-17', '1993-06-17', 'AD_ASST', '90'
'176', '1998-03-24', '1998-12-31', 'SA_REP', '80'
'176', '1999-01-01', '1999-12-31', 'SA_MAN', '80'
'200', '1994-07-01', '1998-12-31', 'AC_ACCOUNT', '90'

We have another table employees(employee_id int, first_name varchar(20), last_name varchar(25) not null, email varchar(25) not null, phone_number varchar(20), hire_date date not null, job_id varchar(10) not null, salary float, commission_pct float, manager_id int, department_id int, constraint emp_pk primary key(employee_id) )

Answer 1

Your Query should be like:

SELECT * FROM job_history INNER JOIN employees 
ON job_history.employee_id = employees.employee_id
WHERE job_history.employee_ID IN
    (SELECT employee_id
         FROM job_history
         GROUP BY employee_id
         HAVING COUNT(employee_id) >= 2
    );

so you missed the alias before the id "WHERE job_history.employee_ID IN..", and the where in change it to what above...

Answer 2

SELECT * FROM EMPLOYEES 
WHERE EMPLOYEE_ID IN
(SELECT EMPLOYEE_ID FROM JOB_HISTORY GROUP BY EMPLOYEE_ID HAVING COUNT(EMPLOYEE_ID) >=2);