试试看。。

select employee_name from
(SELECT    employee_id, COUNT(*) AS total FROM employee_tour 
        GROUP BY  employee_id) as tb 
inner join employee on tb.id_employee = employee.id_employee
where tb.total = (select count (*) from tour)

我将使用两个联接—一个用于统计所有旅行的聚合查询，另一个用于统计员工参加的旅行次数的聚合查询，然后比较它们：

SELECT     e.*
FROM       employee e
JOIN       (SELECT    employee_id, COUNT(*) AS employee_tours
            FROM      employee_tour
            GROUP BY  employee_id) et ON e.employee_id = et.employee_id
CROSS JOIN (SELECT COUNT(*) AS all_tours 
            FROM tour) t
WHERE      employee_tours = all_tours

可以使用join语句

SELECT e.*, t.*
FROM Employee e
INNER JOIN employee_tour et ON et.employee_id = e.employee_id
INNER JOIN tour t ON t.tour_id = et.tour_id

请参阅加入