请大神帮忙SQL改写，not exists 改写成 外连接

这个是Oracle的示例表，emp，dept。分别是14条和4条记录，c表2条。14x4x2=112条记录，这个c表中的manager和7839在emp表中是存在的，所以减去存在的3条记录，最后是109条记录。

目的是通过笛卡尔积补充数据。

其实我在做优化，只是不知道这个怎么改，真的好难啊。
a表1.5亿数据，b表13，c表2。这是40多亿的数据，然后在从中拿不存在的，

SELECT a.empno, a.deptno, a.ename, a.sal, c.job, c.mgr, b.deptno
  FROM (SELECT DISTINCT empno, deptno, ename, sal FROM emp) a,
       dept b,
       (SELECT 'MANAGER' AS job, '9999' AS mgr
          FROM dual
        UNION ALL
        SELECT 'MANAGER' AS job, '7839' AS mgr
          FROM dual) c
 WHERE NOT EXISTS (SELECT 1
          FROM emp t
         WHERE t.empno = a.empno
           AND t.deptno = a.deptno
           AND t.ename = a.ename
           AND t.sal = a.sal
           AND t.job = c.job
           AND t.mgr = c.mgr
           AND t.deptno = b.deptno);

怎么改写成外连接，保证数据量一样

新人没有币，见谅。

我sql水平也一般，不知道写的对不对，没法测试，主要不清楚表结构和你sql语句的目的。
SELECT
a.empno,
a.deptno,
a.ename,
a.sal,
c.job,
c.mgr,
b.deptno
FROM
emp t
INNER JOIN (SELECT DISTINCT empno,deptno,ename,sal FROM emp) a ON t.empno != a.empno AND t.deptno != a.deptno AND t.ename != a.ename AND t.sal != a.sal
INNER JOIN dept b ON t.deptno != b.deptno
INNER JOIN (SELECT 'MANAGER' AS job,'9999' AS mgr FROM dual UNION ALL SELECT 'MANAGER' AS job,'7839' AS mgr FROM dual) c ON t.job != c.job AND t.mgr != c.mgr

你直接把not exist去掉，然后后面一大串条件改成不等于不就行了吗

我现在习惯性会写left join ,我觉得你可以根据查询的先后顺序使用左关内关，可以的，然后再最后加上筛选条件会好点；
(SELECT 'MANAGER' AS job, '9999' AS mgr
FROM dual
UNION ALL
SELECT 'MANAGER' AS job, '7839' AS mgr
FROM dual) c
这一段我有点没有看懂，如果有dual这个表，你可以再语句中写case，这样再表中计算；
SELECT DISTINCT a.empno, a.deptno, a.ename, a.sal, c.job, c.mgr, b.deptno
FROM emp a left join dept b on a.条件=b.条件
再加入C表，可以试一下

SELECT a.empno, a.deptno, a.ename, a.sal, c.job, c.mgr, b.deptno
FROM (SELECT DISTINCT empno, deptno, ename, sal FROM emp) a
inner join dept b on 1=1
inner join (SELECT 'MANAGER' AS job, '9999' AS mgr
FROM dual
UNION ALL
SELECT 'MANAGER' AS job, '7839' AS mgr
FROM dual) c on 1=1
left join emp t on t.empno = a.empno
AND t.deptno = a.deptno
AND t.ename = a.ename
AND t.sal = a.sal
AND t.job = c.job
AND t.mgr = c.mgr
AND t.deptno = b.deptno
where t.deptno is null;