基於變量的過濾器，如果變量中沒有值應用NO過濾器

Question

基於過濾器我想將其應用於要過濾的內容。

例如，如果我有一個名爲p_filter的變量，可能具有值'A'或'B'，我想根據它篩選特定的where子句。

SELECT * 
FROM t1 
WHERE 
id NOT IN (select id from t2 WHERE t1.id = t2.id(+)) --only apply this filter if p_filter = 'A' 
AND id NOT IN (select id from t3 WHERE t1.id = t3.id(+)) --only apply this filter if p_filter = 'B' 

如果變量雖然爲空，我想爲它應用NO過濾器。我嘗試過這樣但它不起作用：

SELECT * 
FROM t1 
WHERE 
CASE WHEN :p_filter != 'A' THEN 1 WHEN id NOT IN (select id from t2 WHERE t1.id = t2.id(+)) THEN 1 ELSE 0 END = 1 
AND CASE WHEN :p_filter != 'B' THEN 1 WHEN id NOT IN (select id from t3 WHERE t1.id = t3.id(+)) THEN 1 ELSE 0 END = 1; 

更新：我很愚蠢，我的意思是如果null應用沒有過濾器！

Answer 1

只要做到：

WHERE 
    --only apply this filter if p_filter = 'A' 
    p_filter = 'A' 
    AND 
    id NOT IN (select id from t2 WHERE t1.id = t2.id(+)) 

    OR 

    --only apply this filter if p_filter = 'B' 
    p_filter = 'B' 
    AND 
    id NOT IN (select id from t3 WHERE t1.id = t3.id(+)) 

    OR 

    -- If the variable though is null, I would like for it to apply both filters 
    p_filter IS NULL 
    AND 
    id NOT IN (select id from t2 WHERE t1.id = t2.id(+)) 
    AND 
    id NOT IN (select id from t3 WHERE t1.id = t3.id(+)) 

----編輯---------

我很抱歉，我笨，我的意思是說，如果null應用NO過濾器！ - user2924127

在這種情況下，只是刪除了最後一個條件，並添加OR p_filter IS NULL：

WHERE 
    --only apply this filter if p_filter = 'A' 
    p_filter = 'A' 
    AND 
    id NOT IN (select id from t2 WHERE t1.id = t2.id(+)) 

    OR 

    --only apply this filter if p_filter = 'B' 
    p_filter = 'B' 
    AND 
    id NOT IN (select id from t3 WHERE t1.id = t3.id(+)) 

    -- I am so sorry, I am stupid, I meant to say if null apply NO filters! 
    OR 
    p_filter IS NULL 

Answer 2

做你的病情的這個 「或」 負像這樣：

SELECT * 
FROM t1 
WHERE 
(:p_filter IS NULL OR :p_filter!='A' OR id NOT IN (select id from t2 WHERE t1.id = t2.id(+))) 
AND (:p_filter IS NULL OR :p_filter!='B' OR id NOT IN (select id from t3 WHERE t1.id = t3.id(+))) 

Answer 3

SELECT * 
    FROM t1 
WHERE ( 
     (p_filter = 'A' and id NOT IN (select id from t2 WHERE t1.id = t2.id(+))) 
      or 
     (p_filter = 'B' and id NOT IN (select id from t3 WHERE t1.id = t3.id(+))) 
      or 
     (p_filter is null) 
     )