SELECT s.dept AS 部门, m.male_sal AS 男薪水, f.female_sal AS 女薪水, t.total_sal AS 合计薪水 FROM sett.t_staff_info s LEFT JOIN ( SELECT dept, SUM(sal) AS male_sal FROM sett.t_staff_info WHERE sex = '0' GROUP BY dept ) m ON s.dept =m.dept LEFT JOIN ( SELECT dept, SUM(sal) AS female_sal FROM sett.t_staff_info WHERE sex = '1' GROUP BY dept ) f ON s.dept = f.dept LEFT JOIN ( SELECT dept, SUM(sal) AS total_sal FROM sett.t_staff_info GROUP BY dept ) t ON s.dept = t.dept GROUP BY s.dept; 报错:ORA-00979:不是 GROUP BY表达式

根据你提供的SQL语句和报错信息，问题出在GROUP BY子句上。要解决这个问题，将所有的非聚合列都添加到GROUP BY子句中。修改后的SQL语句如下：

SELECT s.dept AS 部门,
       m.male_sal AS 男薪水,
       f.female_sal AS 女薪水,
       t.total_sal AS 合计薪水
FROM sett.t_staff_info s
LEFT JOIN (
    SELECT dept, SUM(sal) AS male_sal
    FROM sett.t_staff_info
    WHERE sex = '0'
    GROUP BY dept
) m ON s.dept = m.dept
LEFT JOIN (
    SELECT dept, SUM(sal) AS female_sal
    FROM sett.t_staff_info
    WHERE sex = '1'
    GROUP BY dept
) f ON s.dept = f.dept
LEFT JOIN (
    SELECT dept, SUM(sal) AS total_sal
    FROM sett.t_staff_info
    GROUP BY dept
) t ON s.dept = t.dept
GROUP BY s.dept, m.male_sal, f.female_sal, t.total_sal;

这样，所有的非聚合列都被添加到了GROUP BY子句中，应该能够解决ORA-00979错误。请尝试使用修改后的SQL语句。