SQL - 有條件地評估WHERE子句

Question

我需要獲取WHERE子句才能評估某些語句。例如：

WHERE field_a = field_b AND 
    (CASE WHEN <PARAM>type</PARAM> = 5 
     THEN {field_c = 1 OR field_c = 2} 
     WHEN <PARAM>type</PARAM> = 6 
     THEN {field_c = 3 OR field_c = 4} 
     ELSE field_c = <PARAM>type</PARAM> 

因此，當參數類型= 5時，它只會檢查field_c = 1或2.是否有想法？

Answer 1

WHERE field_a = field_b 
AND (
    (type = 5 AND (field_c = 1 OR field_c = 2)) 
    OR (type = 6 AND (field_c = 3 OR field_c = 4)) 
    OR field_c = type 
) 

這就是你所追求的？

Answer 2

WHERE 
((field_a = field_b)) AND 
(((<PARAM>type</PARAM> = 5) AND (field_c IN (1, 2))) OR 
((<PARAM>type</PARAM> = 6) AND (field_c IN (3, 4))) OR 
((<PARAM>type</PARAM> NOT IN (5, 6) AND <PARAM>type</PARAM> = field_c))) 

Answer 3

這樣做嗎？

Where field_a = field_b AND 
(
    (<PARAM>type</PARAM> = 5 AND field_c IN (1,2)) 
    OR (<PARAM>type</PARAM> = 6 AND field_c IN (1,2)) 
    OR (field_c = <PARAM>type</PARAM>) 
) 

Answer 4

這是我想到的，從帖子的一些靈感後，我意識到我不需要這樣的條件代碼。此外，Param類型可以接受多個值，並以逗號分隔輸出它們，這非常有幫助。

WHERE field_a = field_b AND 
    (field_c in (<PARAM>type</PARAM>)) 

感謝您的幫助！

Answer 5

WHERE field_a = field_b AND 
     CASE WHEN <PARAM>type</PARAM> = 5 THEN 
       CASE WHEN field_c = 1 OR field_c = 2 THEN 1 ELSE 0 END 
      WHEN <PARAM>type</PARAM> = 6 THEN 
       CASE WHEN field_c = 3 OR field_c = 4 THEN 1 ELSE 0 END 
      ELSE 
       CASE WHEN field_c = <PARAM>type</PARAM> THEN 1 ELSE 0 END 
     END = 1