7.2 修改SQL语句 SELECT deptno FROM dept WHERE deptno NOT IN (SELECT deptno FROM emp); ![image image](https://images2015.cnblogs.com/blog/915368/201702/915368-20170206172828947-199066148.png) SELECT deptno FROM dept WHERE NOT EXISTS (SELECT 1 FROM emp WHERE emp.deptno = dept.deptno); SELECT deptno FROM dept MINUS SELECT deptno FROM emp; SELECT dept.deptno FROM dept, emp WHERE dept.deptno = emp.deptno(+) AND emp.deptno IS NULL; ![image image](https://images2015.cnblogs.com/blog/915368/201702/915368-20170206172840666-1500847904.png) |