如何在oracle sql中的where條件中使用case語句？

Question

SELECT DY,ME,NONME 
FROM ( 
    SELECT LEVEL, TO_CHAR(SYSDATE+ROWNUM,'DAY') DY , 0 ME, 2 NONME
    FROM DUAL
    CONNECT BY LEVEL <=10
) 
WHERE ?

如果條件是(ME < NONME) not in ('SATURDAY','SUNDAY')

當(ME> NONME)然后not in ('FRIDAY', 'SATURDAY')

如何使用？

Answer 1

(
  (ME<NONME and .... not in (...)) OR
  (ME>NONME and .... not in (...))
)

Answer 2

假設你的測試數據如下：

select * from tab;

M N DY      
- - --------
A B FRIDAY  
A B SATURDAY
A B SUNDAY  
B A FRIDAY  
B A SATURDAY
B A SUNDAY  

您需要評估蘊涵A --> B可以重寫為NOT A OR B

使用此規則，您的查詢是

select * from tab
where 
-- (ME < NONME) --> not in ('SATURDAY','SUNDAY')
(not (ME < NONME) or DY not in ('SATURDAY','SUNDAY'))  AND
-- (ME> NONME) -->  not in ('FRIDAY', 'SATURDAY')
(not (ME > NONME) or DY not in ('FRIDAY', 'SATURDAY'))
;

給予

M N DY      
- - --------
A B FRIDAY  
B A SUNDAY  

Answer 3

您可以使用包含不區分大小寫的NOT regexp_like()和帶括號的AND運算符和組合這些表達式的OR運算符的查詢：

WITH T AS
(
  SELECT LEVEL, TO_CHAR(SYSDATE + LEVEL, 'DY','NLS_DATE_LANGUAGE=ENGLISH') DY, 0 ME, 2 NONME
    FROM DUAL
  CONNECT BY LEVEL <= 10
)
SELECT *
  FROM T
 WHERE ( NOT regexp_like(dy,'sat|sun','i') AND ME < NONME ) 
    OR ( NOT regexp_like(dy,'sat|fri','i') AND ME > NONME )

演示

Answer 4

如果您熱衷於使用case..when語句，則應按以下方式進行：

.....
Where case 
      when ME < NONME and dy not in ('SATURDAY','SUNDAY')
      then 1 
      When ME > NONME and DY not in ('FRIDAY', 'SATURDAY') 
      then 1
      end = 1

干杯！！