教你使用常用的逻辑公式和恒等式等价改写SQL

今天同事给我一条2秒的SQL看看能不能优化。

原始SQL：

SELECT pk_dept
FROM aaaa
WHERE 1 = 1
  AND ((pk_group = '0001A110000000000JQ6' AND pk_org IN ('0001A110000000001M09')))
  AND (PK_DEPT IN (SELECT t1.ORGID
                   FROM xxxxx t1
                            INNER JOIN (SELECT (CASE WHEN ORGID3 IS NULL THEN ORGID2 ELSE ORGID3 END) orgid
                                        FROM xxxxx
                                        WHERE ORGID = '1001A110000000001U8S') t2
                                       ON t1.ORGID2 = t2.orgid OR t1.ORGID3 = t2.orgid))
  AND (enablestate IN (2))
ORDER BY code;

4 loops=1)
                                                                                                               Heap Fetches: 0
 Planning Time: 258.024 ms
 Execution Time: 2493.882 ms
(1583 rows)

xxxxx   表是一张非常复杂的视图，上面SQL执行计划大概2千行左右，所以本案例就不放整体的计划了。

如果经常做优化的同学对于简单的SQL，相信可以使用瞪眼大法基本定位到语句慢的位置