not exist, not in, left join 的写法，不在。。。之内

SELECT T2.DEPTNO  FROM DEPT2 T2 WHERE NOT EXISTS  (SELECT 1 FROM DEPT WHERE DEPT.DEPTNO = T2.DEPTNO) SELECT T2.DEPTNOFROM DEPT2 T2 WHERE T2.DEPTNO NOT IN (SELECT T1.DEPTNO FROM DEPT T1);   SELECT *  FROM (SELECT T1.DEPTNO T12, T2.DEPTNO T22          FROM DEPT2 T2          LEFT JOIN DEPT T1 ON T1.DEPTNO = T2.DEPTNO) WHERE T12 IS NULL

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