我继承了一个我希望优化的旧SQL脚本,但经过多次测试后,我必须承认,我所有的测试都只是用重复块创建大型SQL。我想知道是否有人可以针对以下模式提出更好的代码(请参阅下面的代码)。我不想使用临时表(WITH)。为了简单起见,我只放了3个级别(表TMP_C,TMP_D和TMP_E),但原始SQL有8个级别。用于NOT IN的TSQL优化代码
WITH
TMP_A AS (
SELECT
ID,
Field_X
FROM A
TMP_B AS(
SELECT DISTINCT
ID,
Field_Y,
CASE
WHEN Field_Z IN ('TEST_1','TEST_2') THEN 'CATEG_1'
WHEN Field_Z IN ('TEST_3','TEST_4') THEN 'CATEG_2'
WHEN Field_Z IN ('TEST_5','TEST_6') THEN 'CATEG_3'
ELSE 'CATEG_4'
END AS CATEG
FROM B
INNER JOIN TMP_A
ON TMP_A.ID=TMP_B.ID),
TMP_C AS (
SELECT DISTINCT
ID,
CATEG
FROM TMP_B
WHERE CATEG='CATEG_1'),
TMP_D AS (
SELECT DISTINCT
ID,
CATEG
FROM TMP_B
WHERE CATEG='CATEG_2' AND ID NOT IN (SELECT ID FROM TMP_C)),
TMP_E AS (
SELECT DISTINCT
ID,
CATEG
FROM TMP_B
WHERE CATEG='CATEG_3'
AND ID NOT IN (SELECT ID FROM TMP_C)
AND ID NOT IN (SELECT ID FROM TMP_D))
SELECT * FROM TMP_C
UNION
SELECT * FROM TMP_D
UNION
SELECT * FROM TMP_E
非常感谢您的帮助。
不是'NOT IN'上'TMP_D'的'WHERE'条款的其他部分和'TMP_E'多余的?由于类别不重叠,如'TMP_B'中定义的,在随后的查询中不需要检查除类别以外的任何内容。这使得它们看起来像只在'UNION'返回时才会过滤'CATEG_4'。 (是的,'distinct'在那里。) – HABO 2013-05-09 15:39:27
@HABO:如果ID是唯一的,它们将是多余的,但事实并非如此。不幸的是,ID不是唯一的,我们可以使用ID = 10和Field_Z = TEST_1的记录,也可以使用ID = 10但Field_Z = TEST_3的记录。 – Bouzouki 2013-05-09 17:16:51