查询s_emp表中所有员工的平均工资: SQL> SELECT avg(salary) FROM s_emp。查询s_emp表中各个部门员工的平均工资及部门名称: SQL> SELECT e.dept_id, max(d.name),avg(e.salary) FROM s_emp e , s_dept d WHERE e.dept_id = d.id GROUP BY dept_id;