獲取'ORA-01427：單行子查詢返回多個行'錯誤

Question

當我嘗試執行此代碼而沒有大小寫，並且正如...和TRANSFORMER IN（SELECT REGEXP_SUBSTR ...）時，它的工作原理。然而，如果TID爲NULL，則添加案例以抓取所有內容會給我帶來錯誤。

(select t.DAY_DATE as D, t.* from pplco_transformer_kva t where 

--NORMALLY '03-MAR-14' IS A VARIABLE 
DAY_DATE = TO_DATE('03-MAR-14')and TRANSFORMER IN(

    --NORMALLY '26113S36753,25761S36662' IS A VARIABLE 
    CASE WHEN '26113S36753,25761S36662' IS NULL THEN(

    (t.TRANSFORMER) 

)ELSE(
    SELECT REGEXP_SUBSTR('26113S36753,25761S36662', '[^,]+', 1,LEVEL) 
    FROM DUAL CONNECT BY 
    regexp_substr('26113S36753,25761S36662', '[^,]+', 1, level) is 
    not null) 
    END 
) 
); 

Answer 1

case語句不返回變量列表。第一部分也不會做你的想法。以下是我認爲你想要的邏輯：

where DAY_DATE = TO_DATE('03-MAR-14') and 
     ('26113S36753,25761S36662' IS NULL OR 
     '26113S36753,25761S36662' IS NOT NULL AND 
     t.TRANSFORMER IN (SELECT REGEXP_SUBSTR('26113S36753,25761S36662', '[^,]+', 1,LEVEL) 
         FROM DUAL CONNECT BY 
         regexp_substr('26113S36753,25761S36662', '[^,]+', 1, level) is not null 
         ) 
    )